Software quality is one of important field in software engineering that related to software satisfaction. In the last years it is an increasing number of electrical substations that areentirely monitored and controlled using software systems. The quality aspects and reliability of monitoring software systemsfrom the energy field is of great issue. SCADA stands for Supervisory Control And Data Acquisition and as its name shows, SCADA is not only a control system, but also encompasses the regulatory level and it could mean that the SCADA is a software package that performs monitoring and control and datamining operations with controllers such as PLCs and other hardware modules. In this project we evaluate the quality ofSCADA system with Bayesian Networks. Bayesian networks have become a popular tool for modeling many kinds of statisticalproblems over the last years. One of main goals of Bayesiannetwork is union uncertainty with expert systems. We can cover uncertainty on calculation of sub-factors by modeling quality with Bayesian networks. This model can evaluate software quality with incomplete and uncertain data.