In this study, we used hCD19 CAR-T cells to treat 19 relapsed/refractory B-ALL patients who previously received mCD19 CAR-T but still had a high level of CD19 antigen expression, including 16 cases relapsed after and 3 cases primarily failed to mCD19 CAR-T, the treatment response at 1 month and follow-up outcomes were evaluated. Here, CD19 is linked to precursor B-cell acute lymphoblastic leukemia.