This is a single-arm, open-label pilot study to evaluate the safety and efficacy of CD19-targeted allogenic CAR-T cells (19UCART) in patients with relapsed/refractory B-cell hematologic malignancies. 12 patients are planned to be enrolled in the dose-escalation trial. The primary objective of the study is to evaluation of the safety and feasibility of 19UCART for the treatment of relapsed/refractory B-cell hematologic malignancies. The secondary objective is to evaluate the efficacy of 19UCART for the treatment of relapsed/refractory B-cell hematologic malignancies. The exploratory objective is to evaluate expansion, persistence and ability of 19UCART to deplete CD19 positive cells in patients with relapsed/refractory B-cell hematologic malignancies.