Abstract: Objective investigate the mechanism of Depression proliferation in human hepatocarcinoma cells by Abscisic acid. Methods detect protein expression o of P53 ,Ki-67 and Cyclin D1 by immunocyte chemistry ; detect mRNA expression of P53 and telomerase by RT-PCR. Results the protein expression level of mtP53 , Cyclin D1 , Ki-67 and the mRNA expression level of mtP53 and hTERT all reduce In cells treated by ABA,HMBA and ABA+ HMBA（P<0.05）.Conclusions ABA depress proliferation of human hepatocarcinoma cell SMMC－7721 ，which mechanism is possible to regulate cell cycle and reduce protein expression of mtP53 ,Ki－67, Cyclin D1and mRNA expression of mt P53,hTERT.

Key words: abscisic acid, hexamethylenebisacetamide SMMC-7721 human- hepatocarcinoma cell, induced differentiation