Abstract: In order to obtain influence regularity of cutting head load to deviation angle of boom-type roadheader during cutting process, a dynamical model of roadheader's deviation angle was established. According to input problem solved by the model, a calculation method of the cutting head load was proposed, and relationship between the cutting head load and pressure of driving cylinders and cutting position of cutting arm was obtained by simulating calculation. The variation of roadheader's deviation angle during cutting process was simulated and analyzed, and influence regularity of the cutting head load to the deviation angle in different cutting conditions and different cutting positions of the cutting arm were obtained: In horizontal cutting condition, the deviation angle increases with increasing of the cutting head load , and it reaches to the maximum when the horizontal angle of the cutting arm is 14°; in vertical cutting condition, the deviation angle decreases with increasing of the cutting head load, and the larger vertical angle of the cutting arm is, the smaller the deviation angle is.