Abstract: To enable doctors to perform surgical operations based on their visual habits according to the laparoscopic visual environment provided by the surgical robot, the kinematic model of the laparoscope arm and the instrument arm of the Minimally Laparoscopic Surgical Robotic System (MLSRS) is studied, and a new kinematics method of instrument arm based on the 3D dynamic visual window navigation is proposed according to the inverse kinematics of the instrument arm with respect to the visual coordinate system of the laparoscope arm. At last, simulation experiments based on the theoretical algorithm and the mechanism model are carried out with Simulink and SimMechanics toolboxes in Matlab, and the simulation results show that the theoretical and actual changes of the kinematics algorithm are equal. Furthermore, multiple sets of data are presented to illustrate the correctness and the feasibility of the kinematics method of the instrument arm.