In connection with the problems that coal mining accounts for water environment pollution and socio-economic development, the main factors was analyzed. From water environment system, ecological system and socio-economic system, corresponding evaluation index system was perfected and became fit for factual situation. Matter-element model of water environment impact evaluation was constructed and used to evaluate four large-scale coal mining areas. The results showed that assessment model in accordance with the objective reality. Compared with other evaluation models, matter-element model is more accurate and comprehensive. By matlab, a calculating program was made and can be dynamically amended.