This is an open-label, non-randomized, multicenter Phase 1/2 trial evaluating a dual CAR-T cell therapy targeting CD146 and HER2 in patients with advanced sarcoma. Participants will receive lymphodepleting chemotherapy with cyclophosphamide and fludarabine, followed by sequential infusion of autologous CD146-specific and HER2-specific CAR-T cells. The Phase 1 portion will employ a dose-escalation design to assess safety and determine the recommended Phase 2 dose, while the Phase 2 expansion will evaluate preliminary efficacy (tumor response and survival outcomes). Approximately 40 patients (children and adults) with relapsed or refractory sarcomas will be enrolled across multiple centers. All participants will be followed for up to 36 months to monitor dose-limiting toxicities, objective response rates, progression-free survival, overall survival, and long-term safety.