• Four-months remission rate [ Time Frame: 4 months ]
  Number of patients reaching Complete Remission (CR) according to National Comprehensive Cancer Network (NCCN, Version 1.2015).
• Number of participants with adverse events (AEs) [ Time Frame: 3 years ]
  Therapy-related adverse events were recorded and assessed according to the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE, Version 4.0).

• Four-months remission rate [ Time Frame: 4 months ]
  Evaluation of remission rate according to National Comprehensive Cancer Network (NCCN, Version 1.2015).
• Number of participants with adverse events (AEs) [ Time Frame: 3 years ]
  Therapy-related adverse events were recorded and assessed according to the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE, Version 4.0).

• Overall survival [ Time Frame: 3 years ]
  OS was calculated from the first infusion to death or last follow-up (censored).
• Event-free survival [ Time Frame: 3 years ]
  EFS was calculated from the first infusion to death, progression of the disease, relapse or gene recurrence, whichever came first, or last visit (censored).
• Relapse-free survival [ Time Frame: 3 years ]
  RFS was calculated from the first infusion to relapse or last visit (censored).
• Quantity of gamma-delta T cells in bone marrow cells and peripheral blood cells [ Time Frame: 3 years ]
  Persistence of γδ T cells assessed by number and phenotype of γδ T cells using flow cytometry assay in peripheral blood and bone marrow from patients
• lymphocyte subsets function assessment of bone marrow cells and peripheral blood cells [ Time Frame: 3 years ]
  Assessment of lymphocyte subsets function using flow cytometry assay in peripheral blood and bone marrow from patients.

• Overall survival [ Time Frame: 3 years ]
  OS was calculated from the first infusion to death or last follow-up (censored).
• Event-free survival [ Time Frame: 3 years ]
  EFS was calculated from the first infusion to death, progression of the disease, relapse or gene recurrence, whichever came first, or last visit (censored).
• Relapse-free survival [ Time Frame: 3 years ]
  RFS was calculated from the first infusion to relapse or last visit (censored).
• Quantity of gamma-delta T cells in bone marrow cells and peripheral blood cells [ Time Frame: 3 years ]
  Persistence of γδ T cells assessed by number and phenotype of γδ T cells using flow cytometry assay in peripheral blood and bone marrow from patients
• lymphocyte subsets function assessment of bone marrow cells and peripheral blood cells [ Time Frame: 3 years ]
  Using flow cytometry assay in peripheral blood and bone marrow from patients.

Inclusion Criteria:

1. History of acute myeloid leukaemia (initially diagnosed by presence of 20% or more blast cells with myeloid or monocytic differentiation confirmed by flow cytometry in peripheral blood or bone marrow)
2. Relapsed or refractory AML. A. AML relapse after intensive chemotherapy; B. AML relapse after allogeneic HCT; C. AML progression on low intensity therapy (low dose cytarabine, 5-azacytidine or decitabine); D. No response to at least 4 cycles of low intensity therapy; E. AML refractory to 2 cycles of induction chemotherapy.
3. Presence of > 5% of blasts in bone marrow or peripheral blood smear
4. Patient not eligible for or does not consent to high dose salvage chemotherapy and/or allogeneic Haematopoietic Cell Transplantation (HCT)
5. Considered suitable for lymphodepleting chemotherapy
6. The patient's peripheral superficial venous blood flow smoothly, which can meet the needs of intravenous drip.
7. Patient's main organs function well. A. Liver function: ALT/AST < 3 times the upper limit of normal (ULN); B. total bilirubin≤34.2μmol/L; C. Renal function: Creatinine < 220μmol/L; D. Pulmonary function: Indoor oxygen saturation≥95%; E. Cardiac Function: Left ventricular ejection fraction (LVEF) ≥40%;
8. Life expectancy of at least 3 months
9. Patient ECOG score≤2, Estimated survival time≥3 months.
10. Ability to be off systemic prednisone and other immunosuppressive drugs for at least 3 days prior to γδ T cells product infusion. Maintenance replacement steroid is allowed.
11. The patients did not receive any anticancer treatments such as chemotherapy, radiotherapy and immunotherapy (such as immunosuppressive drugs) within 4 weeks before admission, and the toxicity related to previous treatments had returned to < 1 level at admission (except for low toxicity such as alopecia).
12. Patient able to understand and sign written informed consent
13. Age 18 years up to the age of 75 (≤ 75)

Exclusion Criteria:

1. Women who are pregnant (urine/blood pregnancy test positive) or lactating.
2. Male or female with a conception plan in the past 1 years.
3. Patients cannot guarantee effective contraception (condom or contraceptives, etc.) within 1 years after enrollment.
4. Uncontrolled infectious disease within 4 weeks prior to enrollment.
5. Active hepatitis B/C virus.
6. HIV infected patients.
7. Suffering from a serious autoimmune disease or immunodeficiency disease.
8. The patient is allergic and is allergic to macromolecular biopharmaceuticals such as antibodies or cytokines.
9. The patient participated in other clinical trials within 6 weeks prior to enrollment.
10. Systemic use of hormones within 4 weeks prior to enrollment (except for patients with inhaled corticosteroids).
11. Have a history of epilepsy or other central nervous system diseases.
12. Having drug abuse/addiction.
13. According to the researcher's judgment, the patient has other unsuitable grouping conditions.