CD19 CAR T cell preparation kit is composed of three parts: T cell activation and expansion unit, T cell purification unit and CD19 CAR gene transduction unit. The T cell activation and expansion unit consists of T cell basal medium and T cell activation reagent, which provides nutrients for T cell culture, and the T cell activation reagent provides T cell activation signals for T cell activation; the T cell purification unit consists of T cell sorting beads and columns, which is capable of obtaining high purity T cells from single blood collection or PBMC; The CD19 CAR gene transduction unit contains CD19 CAR T spot lentivirus and T cell transduction enhancer (Viral E-hancer B), which enables efficient integration of CD19 CAR sequence. This kit is easy to operate, and prepares CAR T cells with high expansion multiplicity and cell viability, CAR gene transduction efficiency and T cell purity.