Regression diagnostic problems have been extensively studied in the context of right-censored survival data but not many for current status survival data. Here the current status survival data, including covariates, an examination time, and an indicator for whether the failure has occurred by the examination time. In this thesis, we develop four graphical or quantitative methods for evaluating the Cox proportional hazards assumption of current status survival data, namely the “log-log survival curve plots”, “observed and expected survival curve plots”, “Cox-Snell residual method”, and “Brier-score method”. The corresponding goodness-of-fit indices for four methods are also proposed. Simulation results reveal good performance of four methods. Three real data sets are analyzed to illustrate the applications of the proposed methods.