Aiming at the problems of complex motion planning, multiple degrees of freedom and difficult control of industrial manipulator apple picking, human hand picking was simulated and a lightweight 3-DOF apple picking manipulator was developed. Firstly, the structural design and kinematic analysis of the manipulator were completed for the requirements of apple picking. The mechanical arm adopted a parallelogram structure, which reduced the rotational inertia of the whole machine through a rear power source, and had a long arm span, a large working space, and small branch interference during movement, which was more suitable for apple picking. Secondly, the Newton-Euler equation was used to establish the dynamic model, and the apple picking simulation of the manipulator was completed. Through the theoretical data of the dynamic model, the stress and strain of the arm and its key components were analyzed to reduce the mass of the manipulator itself. The stress and strain under different lightweight schemes were calculated to select the optimal lightweight scheme. By comparing the simulation data of the manipulator before and after lightweight, the peak driving torque of the bone rod lightweight scheme was reduced by 21N·m and 15N·m, respectively, both of which were reduced by about 20%. The weight of the whole machine was reduced by 1.8kg, which was reduced by 32.1%, and the lightweight manipulator maintained good working ability. According to the optimization results, a physical prototype of a 3-DOF apple picking manipulator was built. The maximum driving torques of the large and small arms were 92N·m and 63N·m through experiments, which basically conformed to the simulation results and verified the correctness of the dynamic model.