In System reliability design, it is essential to know the effectiveness of different design options in improving system reliability. Various Reliability models techniques have been created to evaluate these parameters by applying both analytic and simulation techniques, and this paper reviews those related primarily to reliability optimization design problems. The purpose, type of models used, type of systems modeled, heuristic and metaheauristic techniques will be discussed and serviceability parameters are surveyed. Examples of some of the key modeling issues such as RAP, UMGF and MSS , similarities and differences between various models and tools and can be help to aid in selecting models and tools for a particular tools for a particular application or designing needs for future needs.