Objective: To investigate the relationship between genetic factor and prostate cancer(Pca) risk and the possible cause in it. Methods: The polymorphisms of cytochrome P450 family 17(CYPl7) rs743572, p27 V109 G and androgen receptor(AR) gene CAG repeat length in peripheral blood from 70 cases and 70 controls were detected through the polymerase chain reaction-restriction fragment length polymorphism technique or short tandem repeatpolymerase chain reaction technique. Then, according to the results of case-control study, the recombinant plasmids containing the wild/mutant p27 gene were constructed and transfected Pca LNcap cells. After 24 and 72 h of transfection, the cell proliferative activity was determined by MTT method, cell cycle distribution and apoptosis was detected by flow cytometry, and the expression level of bcl-2, caspase-3 and p27 protein was determined by Western-blot. Results:In three target polymorphisms, only p27 V109 G polymorphism was related to Pca risk(P=0.030, OR=0.202, 95% CI=0.042-0.973). Pca risk of p27-109 G allele was lower than-109 V allele(P=0.006, OR=0.285, 95% CI=0.110-0.737). Cells transfected with wild/mutant p27 gene both showed the higher cells apoptosis rate and the lower cell proliferative activity than mock cells(P<0.05 or 0.01), the regulatory effect of mutant p27 on cell proliferation and apoptosis was stronger than the wild p27(P<0.05). Conclusions: p27-109 G allele that could cause higher p27 protein expression than-109 V allele in LNcap cells, maybe is the protective factor of Pca. Methods: The polymorphisms of cytochrome P450 family 17 (CYP17) rs743572, p27 V109 G androgen receptor (AR) gene CAG repeat length in peripheral blood from 70 cases and 70 controls were detected through the polymerase chain reaction-restriction fragment length polymorphism technique or short tandem repeat polymerase chain reaction technique. Then, according to the results of case-control study, the recombinant plasmids containing the wild / mutant After 24 and 72 h of transfection, the cell proliferative activity was determined by MTT method, cell cycle distribution and apoptosis was detected by flow cytometry, and the expression level of bcl-2, caspase- 3 and p27 protein was determined by Western-blot. Results: In three target polymorphisms, only p27 V109 G polymorphism was related to Pca risk (P = 0.030, OR = 0.202, 95% CI = 0.042-0.973) Pca risk of p27-109 G allele was lower than-109 V allele (P = 0.006, OR = 0.285, 95% CI = 0.110-0.737). Cells transfected with wild / mutant p27 gene both showed the higher cell apoptosis rate and the lower cell proliferative activity than mock cells (P <0.05 or 0.01), the regulatory effect of mutant p27 on cell proliferation and apoptosis was stronger than the wild p27 : p27-109 G allele that could cause higher p27 protein expression than-109 V allele in LNcap cells, maybe is the protective factor of Pca.