OBJECTIVE：To study the effects and mechanism of oncolytic virus M 1（called M 1 virus for short ）inducing the apoptosis of cervical cancer C-33A cells. METHODS ：MTT assay was used to detect survival rate of C- 33A cells that were treated with different titers （0，0.001，0.01，0.1，1，10 PFU/cell）of M 1 virus. C- 33A cells were divided into control group （0 PFU/cell）， low-dose，medium-dose and high-dose groups of M 1 virus（0.001，0.01，0.1 PFU/cell）. After treated with corresponding titers of M1 virus for 48 h，flow cytometry was used to detect the apoptotic rate and infection rate of cells；Western blot was performed to detect the protein expression of C/EBP homologous proteins （CHOP），caspase-12，caspase-3 and cleaved-caspase- 3. RESULTS ： After treated with different titers of M 1 virus，the survival rate of C- 33A cells decreased significantly （P＜0.01），and showed a dose-dependent tr end. Compared with control group ，the apoptotic rate and infection rate of cells in M 1 virus groups as well as the protein expression of CHOP ，caspase-12 and cleaved-caspase- 3（except for medium-dose group ）in M 1 virus medium-dose and high-dose groups were increased significantly （P＜0.01）. CONCLUSIONS ：M1 virus can induce the apoptosis of cervical cancer C-33A cells ，and its mechanism may be related to the activation of endoplasmic reticulum stress pathway.