OBJECTIVE： To study the inhibitory effects of recombinant adenovirus Ad-GFP-C197， which prepared by adenovirus vector system-loading human telomerase reverse transcriptase （hTERT） C fragment （C197）， on the proliferation of 3 kinds of tumor cells in vitro. METHODS： Ad-GFP-C197 was amplified and purified with HEK293 cells. Human gastric cancer cells SGC7901， human breast cancer cells MCF7 and human colorectal cancer cells CaCO2 were infected by Ad-GFP-C197 respectively. Using blank adenovirus carrier （Ad-GFP） as reference， the protein expression of C197 in 3 kinds of tumor cells infected by Ad-GFP-C197 was detected by Western blot assay. The inhibitory effects of Ad-GFP-C197 on 3 kinds of tumor cells were detected by MTT assay. The cell proliferation curve was drawn and the proliferation inhibition rate was calculated. RESULTS： The protein expression of C197 was not detected in 3 kinds of tumor cells infected by Ad-GFP， while significant protein expression of C197 was found in above cells infected by Ad-GFP-C197. The proliferation curves of the 3 kinds of tumor cells infected by Ad-GFP-C197 were significantly inhibited with the time extended， and the proliferation inhibitory rate reached 37.31％-41.42％. CONCLUSIONS： Ad-GFP-C197 shows significant inhibitory effects on the proliferation of SGC7901， MCF7 and CaCO2 cells， which is rapid to make up for the slow effect of other telomerase inhibitors.