Abstract: Objective To determine the expression of chemokine (C-X-C motif) receptor 7 (CXCR7) in five gastric cancer cell lines with various degrees of differentiation, and the effect of silencing CXCR7 on the migration and invasion of SGC-7901 cells. Methods The expression of CXCR7 in gastric cell lines (HGC-27, MGC-803, SGC-7901, BGC-823 and MKN-28) was detected by Western bolt and RT-PCR. The SGC-7901 cells were transfected with liposome of CXCR7 siRNA to silence CXCR7 gene, and then treated with stromal-derived factor-1 (SDF-1)——the ligand of CXCR7. Transwell assay was used for determining the migratory and invasive ability of SGC-7901 cells in the four groups: NC siRNA, NC siRNA+SDF-1, CXCR7 siRNA and CXCR7 siRNA+SDF-1. Results CXCR7 was expressed in the five gastric cancer cell lines, with the highest intensity in SGC-7901. The migrated and invasive cells increased in the NC siRNA＋SDF-1 group and reduced in the CXCR7-siRNA group compared with the NC siRNA group (P CXCR7-siRNA＋SDF-1 group had less migrated and invasive cells than the NC siRNA＋SDF-1 group (P CXCR7 siRNA .