Objective：To construct SiRNA-signal transducers and activators of transcription 3（STAT3） expression vector，to silence protein of STAT3 expression in human colon cancer cell sw620 and to study apoptosis of sw620 after STAT3 interference in vitro. Methods：In this study，short hairpin RNA targeting STAT3 was cloned into pGenesil-1 plasmid vector，named as p-shSTAT3. Forty-eight hours after transfection with p-shSTAT3，the expression level of STAT3 mRNA and protein were measured using RT-PCR and Western blot. Moreover，Hochest 33258 staining was used to measure the apoptosis of sw620 cell after transfection. Furthermore，downstream apoptosis-related targets of STAT3，p53，Caspase 3，Bax，Bcl-XL and Bcl-2 in sw620 cell was investigated by Western blot. Results：Our results indicated that p-shSTAT3 could significantly silence STAT3 mRNA and protein expression in sw620 cancer cells（P=0.000）. Hochest 33258 staining indicated that p-shSTAT3 induced sw620 cancer cell apoptosis（P=0.000） whereas controls had no effects on cell apoptosis（P=0.218）. Knockdown of STAT3 expression induce p53，Caspase 3 and Bax protein expression，inhibit Bcl-XL and Bcl-2 protein expression in sw620 cells. Conclusions：Our data showed that interference of STAT3 expression promote sw620 cell apoptosis，which provide new ideas and targets for the treatment of colon cancer.