Objective:To construct a recombinant prokaryotic vector of GRO--琢 and optimize the condition for expressing GST fusion protein in E.coli BL21(DE3),and discuss the function of GRO--琢-GST fusion protein to promote proliferation of tumor cells. Methods:GRO--琢 gene was amplified by RT-PCR method and inserted into the prokaryotic express vector pGEX-4T-1. The plasmid was transformed into E.coli BL21(DE3) and induced to express fusion protein GRO--琢-GST with IPTG. The fusion protein was detected using SDS-PAGE and Western-blot methods. The fusion protein was purified by GSTrap affinity column,and its function on tumor cells proliferation was detected by CCK-8 method in MCF-7 cells. Results:Recombinant pGEX-4T-1/GRO--琢 vector has been successfully constructed. CCK-8 analysis showed that the fusion protein induced proliferation of MCF-7 cells. And GRO--琢-GST fusion protein with high purity was obtained. Conclusion:The protein has a biological activity to induce proliferation of MCF-7 cells,and the study of GRO--琢-GST protein may facilitate further research on its biological functions.