This is an open-label, nonrandomized, investigator-initiated clinical trial to evaluate the safety, tolerability, pharmacokinetics, and efficacy of anti-CD33/CLL1 CAR-NK cell injection in patients with acute myeloid leukemia (AML), and to determine PK parameters, maximum tolerated dose (MTD), and phase II recommended dose (RP2D) for subjects receiving CAR-NK cell injection. The gene discussed is CD33; the disease is acute myeloid leukemia.