Objective　Exploring how to check the proportional hazards assumption of the Cox model,and the solutions to non-proportional hazards between the covariates and the hazard function.Methods　With a example data set of Ⅲc stage ovarian serous cystadenocarcina,illustrating how to use graphical methods to check the proportional hazards assumption of the Cox model.Results　the predictor of post-surgery administering medicine times violated the proportional hazards assumption of the Cox model.Conclusion　when using the Cox model to analyze the predictors of survival time,checking whether the predictors violate the proportional hazards assumption of the Cox model or not should be paid attention to.