Hybrid-driven mechanism synthesis the constant speed motor and the servo motor as the power source through a multi degree of freedom mechanism. The text study on the trajectory planning of hybrid-driven planar 3-RRR mechanism. Firstly, based on compatible link combinations, all possible basic configurations of planar 3-dof kinematics chains were derived. Based on the requirements of hybrid-driven mode, the kinematics chains were selected one by one Planar 3-RRR mechanism was determined to be the research object finally. Then, based on the conclusions of inverse kinematics analysis, using the cubic spline function on point to point path planning, the servo motor rotation laws were presented. Comparing the different speed situation of constant motor, the influence trends on planning results were analyzed.