As the cucumber harvesting robot works in the non-structure condition, the structure and movement of the manipulator directly determines operating space and picking success. According to the specific cucumber cultivation, the manipulator was designed and its structure parameters were optimized based on the method of the parameters optimization. With the D-H kinematic model, the coordinate transformation was achieved between the Articulation and the Cartesian space, and the Jacobian matrix of velocity was derived. Besides, the model was built in the Articulation space for planning path by means of cubic polynomial interpolation. All the parameters optimized was simulated with Matlab, and the simulation results showed that the harvesting manipulator could reach the positions of 90.5% of the cucumbers in the workspace, moreover, it could move smoothly. 