〔Abstract〕 Objective To investigate the expression of RNA binding protein Poly(rC) binding protein 2(PCBP2) in colorectal cancer tissues and its regulatory effect on proliferation and clone formation of colorectal cancer cells. Methods Immunohistochemistry was used to detect the expression of PCBP2 in 50 pairs of colorectal cancer and its relationship with clinical pathological data. The effect of PCBP2 expression on survival time was observed during four years of follow-up. Specific small interfering RNA targeting PCBP2 was transfected into HCT116 cells by liposome-mediated transfection,and the effect of PCBP2 on proliferation and clone formation of colorectal cancer cells was detected by CCK-8 proliferation assay and clone formation assay. Results Compared with the normal adjacent mucosa to the cancer,the expression of PCBP2 in colorectal cancer was significantly increased(P=0.001),and was associated with lymph node metastasis(P=0.031) and tumor stage(P=0.045). But there was no significant correlation between the PCBP2 expression level and gender,size,cell differentiation(P>0.05). Patients with high expression of PCBP2 survived shorter time of recurrence-free survival(P=0.039) or overall survival(P=0.037) than patients with low PBCP2 expression. After inhibiting the expression of PCBP2,the proliferation(P<0.05) and clone forming ability(P<0.05) of colorectal cancer cells were significantly attenuated. Conclusion PCBP2 is highly expressed in colorectal cancer tissues. The high expression of PCBP2 is closely related to clinical grade. Down-regulation of PCBP2 expression can inhibit the proliferation and clone formation of colorectal cancer cells,providing a new target for prognosis evaluation and effective treatment for colorectal cancer.