Disclosed herein are a pharmaceutical composition and a disease therapy method. The pharmaceutical composition relates to an artificial chimeric antigen receptor (CAR). Specifically, the pharmaceutical composition includes a CAR protein that is highly specific to CD19 antigen, a vector that is capable of inducing a cell to generate the certain CAR 19 protein and a population of a modified mammal cell including the CAR19 protein, the vector or combination thereof. Furthermore, the artificial CAR19 includes a CD19 antigen-binding fragment, a transmembrane domain, and a signaling domain. The CD19 antigen-binding fragment is a single-chain variable fragment (scFv) having specific amino acid sequences. Additionally, the method relates to a cancer therapy by using said modified mammal cells. Furthermore, the method includes the steps of purifying a population of autologous cells, modifying the population of autologous cells with an artificial CAR, and administrating the modified autologous cells.