It puts forward and uses the method to improve grey related analysis in the investment decision of the electric project, introduces the concept of the theory of the gray target, sets up comprehensive difference matrix in order to improve the sensitivity and accuracy of the scheme optimum seeking while calculating. Then it fixes every index weight through membership degree, and then calculates and arranges in an order to the weighted average comprehensive value. It can offer the optimized-select scheme for investment decision of the electric project according to its appraisal result.