When many county power grids are constructed and optimized under unified arrangement, the development of the construction program is directly affected by the county power grid evaluation system. Traditional power grid evaluation system lacks in reality guidance due to insufficient consideration and larger subjectivity. In order to solve these problems, this paper provides a grid of county power grid evaluation system. This system can introduce micro-analysis based on principal component analysis (PCA) and conduct macro-guidance based on hierarchical cluster analysis (HCA). Multiple evaluation indexes are made to reduce its dimension by PCA and endow principal component weight to each index without subjective factors. Thereby, a comprehensive assessment system for county power grid is built to gain scores and rankings which can reflect their pros and cons of degree in safety, economy, reliability, adaptability and quality. And then, these scores are clustered based on HCA layer by layer, and the ranking location is backtracked which is gained by PCA, so as to cluster weak indicators of county power grid’s different index modules, and combined load and local county economic development, appropriate development path is developed. Application results show that this county power grid evaluation system based on PCA and HCA is an effective solution.