The present invention discloses a method for establishing a colorectal cancer p73 reporter gene cell line, specifically including: first designing a site-specific sgRNA sequence of a p73 gene and cloning same into a plasmid PX459; integrating a homologous recombination sequence of the p73 gene and a green fluorescent protein DNA fragment (EGFP), and transforming the plasmid and the integrated fragment together into a colorectal cancer cell line HCT116 by electroporation; performing signal cell screening through a flow cytometer to obtain EGFP-expressing cells, and amplifying a monoclonal cell line; and identifying a positive p73 reporter gene cell line through PCR identification and Western blot, among screened EGFP-expressing cell lines. The colorectal cancer cell line p73 gene and the EGFP are co-expressed, and the expression level of the EGFP is highly consistent with that of the p73 gene. Therefore, the expression level of the p73 gene can be accurately determined by detecting changes in the expression level of the EGFP. The method for establishing the cell line in the present invention is simple, easy to implement, high in efficiency and precise in gene site positioning.