At present，there are some problems in the evaluation of education quality at county level，such as unclear concept and connotation，indistinct evaluation focus and improper methods. The main reason is that it still focuses on the improvement of school-running and enrichment of connotation rather than the optimization of education ecology. Therefore，the authors believe that the core of education evaluation at county level is to optimize the education ecology，and put forward the concept of structural quality. It is suggested that to optimize the county-level education ecology，it is necessary to evaluate the education quality at county level by integrating the process-based quality which reflects the level of school-running and the result-based quality which reflects the development of students through the three dimensions of education ecology—equity，balance，and quality. Practice has proved that structural quality can effectively contribute to the move of education quality at county level towards high quality，education balance and equity.