Abstract: Software reliability in the software development process is an important issue. Software process improvement helps in finishing with reliable software product. In this field, SPC (Statistical Process Control) is a method of process management through application of statistical analysis which involves and includes the defining, measuring, controlling and improving of the processes. The proposed process involves evaluation of the parameter of the mean value function and hence the mean value function of infinite and finite failure model in order to develop appropriate mean control chart was considered. In this study, a control mechanism, based on time between failures observations using Rayleigh distribution property was proposed which is based on Non Homogeneous Poisson Process (NHPP).