The invention discloses a mining method for deterioration coal under intrusion of igneous rock, which uses a backwards retreating comprehensive mechanization coal mining method of scientific matching use of three machines (a coal mining machine, a hydraulic support and a scraper conveyer), and concretely comprises the steps of charging coal by the coal mining machine, moving support and pushing running. The coal mining machine employs an end part beveling feed mode that two ends of a working face enable inclined cutting on triangle coal; the coal mining machine group cuts two cuttings by one reciprocation; supports moving is lagged behind the coal mining machine group rear roller by 3 to 5 supports, wherein the unit advance is 0.6m, the center distance of the supports is 1.5m; the scraper conveyer is lagged behind the coal mining machine by 10-15m, and the distance of a coal shoveling plate of the scraper conveyer to a coal wall is greater than or equal to 200mm. According to mass theoretical analysis calculation and numerical simulation calculation, each preferable parameter during the mining process can be obtained, thereby the mining of the deterioration coal seam with characteristics of safety, high efficiency and high recovery rate under the intrusion of igneous rock can be realized.