Abstract: The apoptosis effect and mechanisms of the surface mucus polysaccharide of loach (PML) on human gastric cancer SGC-7901 cell were explored.PML was isolated and purified by Sevege, and was identified by ultraviolet spectrophotometry, gel chromatography and high performance liquid chromatography before acting the role in SGC-7901 cell.Identified the inhibitive effect of PML on SGC-7901 cell by MTT, observed changes in cell morphology using optical microscope, detected cell cycle and apoptosis by flow cytometry, and detected changes of Bax, Bcl-2 protein expression by Western Blot.The results showed that it was high purity and single composition to extract PML by Sevege.The inhibition gradually increased with the increase in concentration of PML and time when the SGC-7901 cells were treated with 10～270μg/mL of PML for 24, 48, 72h.The flow cytometry showed that the apoptosis rate gradually increased with the increase in concentration of PML and time.Western blot detection indicated that Bcl-2 and Bax protein expression enhanced and reduced respectively with the increase in concentration of PML and time after the cell processing of 10～270μg/mL of PML for 24 and 48h, which explained that PML could promote the apoptosis of SGC-7901 cells and the mechanism was related to gene regulation of Bcl-2 and Bax.