Since the development of public service-oriented government portal websites have been advocated by governments all over the world, it will not only benefit the development but also enrich the theories, methods and practices to evaluate the performance of the websites. However, problems exist. Firstly, the index system doesn't highlight public service and is not comprehensive. Secondly, the method to derive the weight of each index is subjective. At last, the method to calculate the final score cannot deal with ambiguity. To address the problems, a framework and an index system for the public service-oriented performance evaluation of government portal websites are proposed, which guide the future research and provide a base for the research.