Abstract: The main tasks of software verification and validation (V&V) for the safety digital I&C system of nuclear power plant (NPP) are to inspect any possible defect, evaluate the potential risk and hazard of the software, and propose the feasible solution, by which the quality of product is guaranteed and improved. During the V&V life cycle process, the selected V&V tools and methods would have a direct impact on the effectiveness of V&V activities. In this paper, the software V&V models were proposed for two different types of NPPs including the new design ones and the reproduction design ones, from the viewpoint of functions of the safety digital I&C system of NPP. The key factors of the software V&V activities were summarized and the relevant methods and tools were analyzed.