This is a single-arm, open-label, phase I/II clinical trial initiated by investigators to evaluate the safety, tolerability, and preliminary efficacy of CD7-targeted chimeric antigen receptor T cells (CD7 CAR-T) combined with autologous stem cell transplantation (ASCT) in patients with relapsed or refractory CD7-positive T-cell lymphomas. Phase I adopts a standard 3+3 dose-escalation design to determine the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). Phase II expands at the RP2D to further assess efficacy. The study includes lymphodepletion chemotherapy, ASCT, and sequential infusion of CD7 CAR-T cells. The primary objectives include: (1) Evaluate safety/tolerability of CD7 CAR-T + auto-HSCT in relapsed or refractory CD7-positive T-cell lymphomas. (2) Determine MTD and RP2D. The secondary objectives include: (1) Assess efficacy (overall response rate, complete response, duration of response, progression-free survival and overall survival. (2)Characterize PK/PD profiles. (3)Investigate anti-tumor mechanisms.