This is a single-arm, open-label, dose-escalation study to explore the safety, efficacy, and cytodynamic characteristics of the drug, and to initially observe the efficacy of the drug in subjects with relapsed/refractory B7-H3-positive acute myeloid cell line leukemia.

Eligible subjects will receive 1.0×10^8 CAR gdT, 2.0×10^8 CAR gdT, 4.0×10^8 CAR gdT, or additional doses may be added at the discretion of investigator and sponsor.

Inclusion Criteria:

• (1) Age≥ 18 years old, gender is not limited;
• (2) expected survival time≥ 3 months;
• (3) ECOG score 0-1 points;
• (4) Acute myeloid leukemia was clearly diagnosed during screening, and tumor cells were positive for B7-H3 expression;
• (5) Subjects with relapsed/refractory acute myeloid leukemia who have failed standard treatment or lack effective treatment methods.
• (6) Coagulation function, liver and kidney function, cardiopulmonary function meet requirements.
• (7) Be able to understand the trial and have signed the informed consent form.

Exclusion Criteria:

• (1) Malignant tumors other than acute myeloid leukemia within 5 years before screening;
• (2) Those who test positive for virus and syphilis;
• (3) Severe heart disease: including but not limited to unstable angina, myocardial infarction (within 6 months before screening), congestive heart failure (New York Heart Association [NYHA] classification≥ grade III), severe arrhythmia;
• (4) Unstable systemic diseases judged by the investigator: including but not limited to severe liver, kidney or metabolic diseases requiring drug treatment;
• (5) Active infection or uncontrollable infection requiring systemic treatment within 7 days prior to screening;
• (6) pregnant or lactating women, female subjects who planned to become pregnant within 2 years after cell reinfusion or male subjects whose partners planned to become pregnant within 2 years after their cell reinfusion;
• (7) Subjects who were receiving systemic steroid therapy within 7 days prior to the year or who were judged by the investigator to require long-term systemic steroid therapy during treatment (other than inhalation or topical use);
• (8) Have participated in other clinical studies within 1 month before screening;
• (9) There was evidence of central nervous system invasion during subject screening, such as tumor cells detected in cerebrospinal fluid or imaging showing central infiltration;
• (10) Those who have graft-versus-host response and need to use immunosuppressants;
• (11) Those with a history of epilepsy or other central nervous system diseases;
• (12) Patients with primary immunodeficiency diseases;
• (13) situations that other investigators consider unsuitable for enrollment.