Abstract: Objective: To investigate the proliferation of human cervical carcinoma cell line （Hela） affected by the different concentrations of L-arginine that acts as the donor of nitric oxide. Methods: The MTT assay had been used to detect the proliferation of Hela cells and Griess assay to measure the cellular metabolites of nitric oxide derivatives. Results: L-arginine increasd NO₂ concertration in culture medium, 1-30mmol/L L-arginine inhibited the activity of Hela cells, under 50-100 the mmol/L enhance the activity of the cells, but the growth style was changed from adhere to the wall to the flouting. Conclusion: the L-arginine possesses the bi-direct effect on tumor cell proliforation.