The simulation system VV&A is an important activity aimed at credibility evaluation of the simulation system's whole life cycle and one of the key techniques and difficult problems of simulation system research and development. In the paper, the key issues concerning VV&A are deeply studied including the concept system of simulation system VV&A , the process model of simulation system VV&A, and the technology framework of simulation system VV&A standard / norm. The researches provide the countermeasure and reference to the research of complex simulation system VV&A standard.