An autopsy is not simply the patient's last medical intervention but in addition to determining the cause of death, it also provides information about the deceased patient's underlying health. The natural process of the body's breakdown following death, starting at the cellular level, is known as post-mortem change. Complex cellular and biochemical phenomena are involved in the process. The changes that begin right away after death continue for a considerable amount of time at various rates for various organs. Numerous intrinsic and extrinsic factors have an impact on the beginning and severity of these changes. The purpose of this research is to review the available information about classification of post-mortem changes and factors affecting it. Post-mortem changes are further divided into three classes, Immediate changes, early changes and late changes. After cardiac and respiratory failure, early post-mortem changes including rigor mortis and post-mortem lividity occur. However, tissue metabolism continues for a few hours after death. Supravital reactions, time-dependent post-mortem lividity, and rigor mortis criteria are used to estimate the time since death. Estimating the post-mortem interval or time since death, is one of the main aims of the forensic autopsy, requires an understanding of post-mortem changes. Many exogenous and endogenous factors can lead to degradation. Animal predation, the environment, and mechanical injury are extrinsic causes, whereas autolysis, putrefaction, and decay are endogenous factors. However, despite the importance of post-mortem findings the literature available is very limited more research in future can be a significant contributor.