Methyl-CpG-binding protein 2 (MeCP2) is a DNA methylation-related gene of the methyl-CpG-binding protein family. Here, we investigated the epigenetic function of the MeCP2 in SaOS2 and U2OS cell lines, and explored the antitumor effects of the gene silencing for osteosarcoma. In this study, chromatin immunoprecipitation assay was used to detect MeCP2 binding activity with TSSC3 gene. RT-PCR and western blot assay were used to analyze the MeCP2 expression in osteosarcoma cell lines after transfection with LV-MECP2-RNAi. Transwell invasion and migration assays were used to detect the cell invasion and migration. The cell apoptosis was examined by using the flow cytometry assay. The tumor size was also assessed to determine the therapeutic effects of gene silencing. The results indicated that MeCP2 indicated the highest combining power with TSSC3 gene. LV-MECP2-RNAi could decrease MeCP2 level in tumor cells compared with the untreated cells (P < 0.05). LV-MECP2-RNAi inhibited the U2OS and SaOS2 cells invasion and migration compared with the control cells (P < 0.05). LV-MECP2-RNAi triggered the U2OS and SaOS2 cell apoptosis, and inhibited the cell proliferation significantly compared with the control cells (P < 0.05). The gene silencing of RNAi could also decreased the tumor size significantly compared with untreated cells (P < 0.05). In conclusion, silencing the MeCP2 gene could block the MeCP2 expression and inhibit the tumor cell migration, invasion, and proliferation, and decreases the tumor size by inducing the apoptosis of the tumor cells.