By progress of science and advanced equipment productions these days, and also creating a competitive environment in the international marketing, high quality systems and designing and manufacturing products has gained system designer’s attention. Reliability’s role is the guarantee to quality. In other words continues optimal quality of a product during time. One of the most important and main ways of improving system’s reliability is to use supporting components, like when some the supporting components are added alternatively to the main components ,so that in the event of main components corruption the system doesn’t stop working. In redundancy allocation problem, quality determination and redundant components type considering weight and cost limits and maximizing total system’s reliability is the purpose.