Abstract: ObjectiveTo investigate suppression effect of hydrazine demethylation on invasive activity of human cervical cancer cell lines HeLa（HPV18 type）,CaSki and SiHa（HPV16 type）. Methods Invasive activity of HeLa，CaSki and SiHa cell lines of human cervical cancer treated with Hydralazine(Hyd) of different concentration were analyzed by using millipore cells invasion room method. The methylation status of 5'CpG island in the promotor of APC and CDH1 genes in the three cell lines were analyzed using MSP method before and after Hyd treatment. The expression of APC and CDH1 mRNA in the three cell lines was studied by FQ-PCR methods before and after Hyd treatment. Results Comparing with the normal control group，suppressing invasive activity of HeLa，CaSki and SiHa cell lines of human cervical cancer treated with 10 μmol/L Hyd have no statistical significance，while the group with 20 μmol/L Hyd have statistical significance (P<0.05)，and the group with by 40 μmol/L Hyd have significant difference (P<0.01). Different drug density being compared，the group treated with 40 μmol/L Hyd have significance suppression.After 40 μmol/L Hyd treatment for 48h，methylation of the APC and CDH1 genes of these three cell lines was at different levels of demethylation. Expression of APC and CDH1 mRNA was up-regμlated in these three cell lines after treatment. The expression of APC mRNA in HeLa，CaSki，and SiHa cell lines increased 5.89-，8.46-，and 0.97-fold，and CDH1 mRNA increased 4.82-，5.90-，and 8.46-fold，respectively. Conclusion Hydralazine has an effect on suppressing invasive activity of HeLa，CaSki and SiHa cell lines of human cervical cancer, one of the mechanisms of action may be demethylation.