A new method has been put forward to automatically adjust height of drum-typeshearer.The principle of this rnethod is that the boundary of coal and rock is recognized with thepressure changes resulting from the height adjustment of the oil cylinder exerted by the cutting forceswhile the shearer drum is cutting the pure coal seam and the rock.With the help of this the corre-spondent hydraulic serving system can be controlled to adjust the height of shearer drum automati-cally.In this paper, a mathematical model is established a nd experiments and researches have been al-so carried out.