Abstract: To study the force characteristics of support boots of a shearer under the conditions of large span and over constraint,the static model of the shearer under 18 loads was established by considering the factors including the roll and pitch angles. Aiming at the uncertainty of model coefficient matrix,an improved aggregation function was proposed to deal with the absolute coefficient matrix of the shearer static equations,and the modified smooth nonlinear equations were obtained. The three-axis forces of the drum obtained by the cutting experiment were input into the static equations as the excitation,the Levenberg-Marguardt method was used to solve the equations,and the theoretical values of boots were calculated and compared with the actual measured values. According to the error range less than 10% ,the cor- rectness of the theoretical model was verified. By applying the control variable method,the roll and pitch angles of the shearer were changed respectively to research the force characteristics variation of the shearer boots. The results show that the influences of the roll angle variation to the lateral forces of the front and rear guiding sliding boots were big- ger,and to the support forces of the front and rear sliding boots and the flat sliding boots were smaller. The forces of all boots were influenced by the shearer roll angle variation,and the force variations were approximately linear.