In order to find out the reason that Xixizhuang Mine coal metamorphism, through a large number of drilling and the reveal of mine data, the diabase sills rock intrusion age, occurrence characteristics and spatial distribution was studied, the coal quality variation of coal seam was analyzed. Diabase sills and its influence on coal seam were discussed. The diabase in late Yanshan movement in the form of bedrock bedding into the Jurassic pagoda coal zones, resulted in abnormal ancient geothermal field making coal metamorphism occurred again. The coal class distribution and occurrence characteristics of diabase bed space was completely consistent. Results showed that the regional metamorphism was the main factor of Yuxian mining area metamorphism, diabase invasion was the direct cause of fine coal mine coal metamorphism diversity.