The space position error of big angle combined motion (BACM) is large for upon platform of ball screw transmission Stewart platform (BSTSP). The kinematics simulation method is proposed for the problem above based on ADAMS software. In ADAMS software, the virtual prototype model is established, the restraints are added, the drives are set in the centre point of upon platform, the stretch length and velocity cures of six motor-driven cylinders are obtained for upon platform realizing the space position of BACM. This kinematics simulation method can solve the problem above. It improves the design efficiency and avoids the calculation error of tradition method by coordinate conversion and matrix differential, the developing cost is reduced also. The kinematics simulation method provides an optional project for designing control algorithm of BSTSP realizing the BACM.