Abstract: Existing automatic coal cutting methods of shearer lack appropriate mathematical model and algorithm and cannot realize long-term and continuous automatic coal cutting, which restrict improvement of working face automation level. For above problems, function relationships among shearer attitude, shearer position and cutting height were analyzed in 3D coordinate system. Motion equations of shearer were built based on stationary and moving coordinate systems separately. Memory coal cutting algorithms of double demo knives and single demo knife were presented as well as their implementation methods in the moving coordinate system respectively. The memory coal cutting algorithm of single demo knife is applied in No.31112 working face of Jinjie Coal Mine for automatic coal cutting in the whole working face including triangle area, which verifies correctness, effectiveness and robustness of the algorithm.