The invention discloses a mechanical coal mining system and method for a steeply-inclined thick coal seam, and relates to the technical field of coal mining. The mechanical coal mining system and method mainly aims to improve the yield, the mining efficiency and the coal mining safety of a coal mining working face. According to the main technical scheme, the coal mining system comprises the working face, a transportation roadway, an air return roadway, a shield bracket, an excavation and mining machine, an excavator and a scraper conveyor; the transportation roadway and the air return roadwayare arranged on the two sides of the working face in an inclined mode, one ends of the transportation roadway and the air return roadway communicate with the working face, and the other end of the airreturn roadway conducts air return through an air return cross-cut; the working face is arranged along the trend of the coal seam, the coal wall of the working face is in the horizontal state, and the working face is excavated downwards along the coal seam in an oblique mode; the shield bracket is supported between a roof and a floor of the coal seam and used for supporting a goaf; the excavationand mining machine and the excavator are located on the working face; and the scraper conveyor is located on the working face and used for conveying coal transferred by the excavation and mining machine to the transportation roadway. The mechanical coal mining system and method is mainly used for mechanical mining of the steeply-inclined thick coal seam.