In order to comprehensively, accurately and reasonably allocate the investment amount of the countylevel distribution network (110 kV and below), this paper builds a countylevel distribution network investment benefit indicator system by considering the county investment benefits of a new round investment firstly. Then, the indicator system is evaluated by using the fivelevel set pair analysis model. Furthermore, Based on the singleindex evaluation result and the comprehensive evaluation result of the indicator system, the investment allocation adjustment factor model is constructed. In the end, the countylevel grid investment allocation amount is analyzed and calculated combining with the future electricity demand. The example shows that the proposed method can be used to formulate the investment strategy precisely for the countylevel distribution network to realize the refined planning of the countylevel distribution network and the scientific, reasonable and effective use of limited funds.