Abstract: Objective To study the effects of MeCP2 in proliferation of lung cancer cell lines A-549. Methods By the sequence of human MeCP2 gene in GeneBank, the oligonucleotides encoding shRNA targeting the MeCP2 gene were designed and sythesized， then directionally cloned into plasimd pSliencer-2.1-U6, confirmed by PCR and DNA sequencing analysis，the recombinant plasimd was transfected into A549 cell line by lipofectamine TM2000. The expression of MeCP2 at mRNA and protein was examined by RT-PCR and Western blot respectively, the changes of cell proliferation were observed by MTT assay. Results The two shRNAs expressing plasmids targeting the MeCP2 gene were constructed and transfected into A549 cell line successfully. The expression of MeCP2 in mRNA and protein levels was reduced visibly. The down regulation of MeCP2 inhibited the proliferation of A549 cell significantly. Conclusion The MeCP2 protein plays an important role in the proliferation of lung cancer cell. 