Chk1 and Chk2 play major role in cell cycle checkpoint signaling pathway, which are mainly involved in G2/M cell cycle checkpoint signal transduction. Firstly, the siRNA targeting at Chk1 or Chk2 gene was transfected into human gastric cancer BGC823 cells for 24 h before 15 mg/L DADS was added. Then, the mRNA and protein expression of Chk1 or Chk2 was detected by Real-time PCR and Western-blot respectively. Cell cycle rates and expressions of CDC25C and cyclinB1 were determined by FCM and Western blot respectively. The results showed that the Chk1 or Chk2 expression was inhibited in Chk1 or Chk2 siRNA-transfected group, in which the Chk1 or Chk2 expression at mRNA level was reduced 84.7% and 69.0% respectively and the protein expression of Chk1 or Chk2 was reduced 73.4% and 78.5% respectively as compared with that in empty control group (P < 0.05). Then it was investigated whether Chk1 and Chk2 proteins could influence cell cycle regulation by knocking down their expressions in BGC823 cells. Further investigation revealed that inhibition of the Chk1 expression in Chk1 siRNA transfected group cut down the proportion of the cells in G2/M phase from 58.1% to 10.4% in BGC823 cells after 24 h induced by DADS (P < 0.05).While inhibition of the Chk2 expression in Chk2 siRNA transfected group had little effect on G2/M arrest after treatment with DADS(P > 0.05). Western blot showed that although DADS decreased expression of CDC25C and cyclinB1 in untransfected cells, inhibition of expression of CDC25C and cyclinB1 treated by DADS was blocked by Chk1 gene silence (P < 0.05). On the contrary, Chk2 gene silence can not do so. These results suggest Chk1 gene silence could abrogate G2/M arrest induced by DADS in BGC823 cell line, and Chk1/CDC25C/cyclinB1 pathway was involved at the G2/M arrest induced by DADS.