The present disclosure relates to a scFv amino acid sequence capable of recognizing CD19 antigen and a nucleotide sequence encoding the same, and also relates to a chimeric antigen receptor, a nucleic acid encoding the same and a cell expressing the same, and their uses in the manufacture of a medicament for treating tumors. The chimeric antigen receptor of the present disclosure comprises at least one extracellular domain, an optional transmembrane domain and at least one intracellular costimulatory signaling domain, wherein the extracellular domain comprises a CD19 antigen-recognizing and binding domain. The chimeric antigen receptor of the present disclosure has been humanized, resulting in a longer survival period in vivo, and a corresponding extended complete remission period in patients.