In order to meet the demands of diversified settlement modes and settlement mode adjustment for provincial power generation enterprises， a settlement system design method is proposed. In this method， the problems of settlement object diversity and price fluctuation are solved by building the mapping relationship between settlement unit and physical unit， and management of clearing prices. The problem of settlement modes diversity is solved by putting the different settlement algorithms in algorithm library by the definition and configuration of settlement units. The software flow chart and application functions implementation of the system are given. The system has such characteristics as configurability， expansibility， and reusability. The system designed has been successfully used in provincial electricity market， and in meeting the settlement demands.