A 3-DOF parallel 3-PRS mechanism, which could realize one translational and two rotational motions as well as support secondary mirror used in laser beam focusing, was proposed. According to the analysis of motion mode, traditional Euler angle for describing the motion of moving platform was adopted, and based on that, kinematic model of a 3-DOF mini mechanism was built to analyze its inverse kinematics performance. The inverse dynamics modeling with principle of virtual work was derived by introducing a mass distribution factor of link legs. Based upon the established model, two control systems were implemented on the mini 3-PRS parallel manipulator. Then, control accuracy of the robot was obtained by combining ADAMS/Control with MATLAB/Simulink. Moreover, the quality of laser speckle was evaluated by applying the mini 3-PRS robots into an actual optical system. The derived results prove that a mini 3-DOF mechanism can fulfill the design requirements of the structure for supporting secondary mirror.