Objective:To construct IL-15 knockout MGC-803 cells by using CRISPR/Cas9 genome engineering technology. Methods:Guid RNA was designed by trageting the second exon of IL-15 gene,which encoded its homeodomains. PX458-gRNA recombinant plasmid was constructed and transformed into competent Stbl3. To confirm the efficitiveness of designed gRNA,the recombinan was screened and sequenced. The expression of IL-15 gene of MGC-803 cells sorted through FACS was detected by ELISA, and the cell cycle was detected by FACS. Results:Compared with negative control group,the expression of IL-15 transfected with PX458-IL-15-gRNA plasmid was significantly lower (P < 0.001). Conclusion:The IL-15 konctout gastric cancer cell line(MGC-803 cells)had been successfully constructed by using CRISPR/Cas9 system,which lays the foundation for further study of the mechanism and founction of IL-15 in tumors.