Chinese government fiscal investment in agriculture does not have effective assessing measures and measurable assessing indexes. It is necessary to establish a suite of index system which can be used to evaluate the benefit of government fiscal investment in agriculture. Following rational principles, the index system evaluating the benefit of Chinese government fiscal investment in agriculture is constructed by applying Delphi Method. The index system consists of three sectors, and eighteen indexes. After indicating three key links of applying the index system, two methods: scale evaluation method and index comparison method are offered. In the end, the index system and the evaluation methods are illuminated by means of living example.