Objective To observe the expression of RAR-β gene in SiHa, HeLa,C33A and CasKi cell lines of cervical carcinoma and to investigate the role of methylated RAR-β in its expressive defection. Methods Reverse transcription polymerase chain reaction (RT-PCR) was used to analyze the mRNA expression of RAR-β gene. Immunohistochemistry and Western Blot were used to analyze the protein expression of RAR-β gene in four cervical cancer cell lines as well as the influence of 5-Aza-cdR on gene expressive defection. Methylation specific PCR (MSP) was used to detect whether there was the methylation in RAR-β gene in four cell lines. The change of RAR-β gene methylation state was also observed by MSP. The cell proliferation rate influenced by the 5-Aza-cdR was observed by MTT assay. Results The expression of RAR-β mRNA and protein in SiHa, HeLa and CasKi cell lines of cervical cancer was silent or decreased, whereas its expression was detected in C33A cell line. By using MSP method, it was found that there was RAR-β gene methylation in those three cell lines, whereas there was no RAR-β gene methylation in C33A cell line. After treated with the 5-Aza-cdR, methylated RAR-β gene was partly demethylated, and RAR-β mRNA and protein were re-expressed in the previous three cell lines in which RAR-β gene expression was silent or decreased. The 5-Aza-cdR treatment could supress cell proliferation as well. Conclusion The RAR-β gene expressive defection plays an important role in the carcinogenesis of cervical cancer. The abnormal RAR-β gene methylation in the the promotor region has an important role in gene expressive defection. The cell proliferation can be supressed by demethylated treatment.