The expression of octamer binding factor 4 (Oct4) gene in bladder cancer cell line T24 and its effects on the biological characteristics of the cells were investigated. RT-PCR and Western blot were employed to detect the expression of Oct4 in T24 cells. The changes of biological characteristics in T24 cells were analyzed before and after gene-silencing by Boyden chamber and MTT. The results showed that the expression of Oct4 gene was detectable in T24 cells by RT-PCR and Western blot. The expression of Oct4 gene and protein was down-regulated by siRNA, and average number of transwell cells in interference group, negative control group and blank control group was 101.40+/-4.56, 104.20+/-10.03 and 111.00+/-11.90, respectively. There was significant difference in the proliferation ability of the cells from 48 h, 72 h to 96 h after the interference by siRNA between interference group and negative group or blank control group (P<0.05). It was suggested that Oct4 gene was related with proliferation ability of T24 cells, but not with invasive capability.