Abstract: How to calculate grid infrastructure investment to meet the social, economic development needs and enhance investment efficiency. Grid investment calculation has gradually become the urgent problem faced by the grid corporation. Grid infrastructure investment calculation is difficult, due to influences with many factors, complex relationships and difficulty of grid development demand forecasting. This paper studies a grid infrastructure investment calculation model based on gray prediction. Firstly, an indicator system for grid infrastructure investment calculation is built by analyzing the relationship between indicators and grid infrastructure investment. Secondly, a gray model based indicator prediction model is built to predict the development trend of indicators which are closely related to grid infrastructure; the analytic hierarchy process (AHP) is used to determine each index change impact on investment; the amount of grid infrastructure investment is calculated by using the indicators predictive value and determine indicators,. Finally, the validity and rationality of the proposed calculation model are verified by the example of a grid infrastructure investment calculation. The proposed calculation model is extremely important theoretical and practical significance for the coordination of grid infrastructure investment and planning the scale of investment.