Abstract: In this paper, 3-TPT parallel robot is taken as the research object, the inverse kinematics solution of the parallel mechanism and the forward kinematics solution of the constraint structure are established, and the expressions of the limit constraints of the connecting rod and hinge are given. Then, the set of workspace points is obtained by numerical method, and the definition of effective workspace is determined according to the actual application environment of parallel robot. Finally, aiming at the maximum volume of effective workspace, the length of connecting rod and the rotation range of restraint structure are optimized based on the basic structure size of parallel robot. The results show that the optimized volume of effective workspace is about 1.5 times of the initial volume.