Abstract: In order to improve the installation efficiency of prefabricated building wall panels and to reduce construction intensity, a new type of prefabricated building wall panel installation machine is designed by using the theory of controllable mechanisms. Considering the heavy-duty and long-term operating conditions of prefabricated building wall panel installation machines, an optimized design has been carried out for its gantry pitching mechanism. With wallboard installation machine as the research object, solved were the functional relationships between the displacement, angular velocity and, angular acceleration of the gantry flipping angle and the working length, velocity and, acceleration of the gantry oil cylinder. The prerequisite for dynamic optimization design was provided. The dynamic static model of the mechanism was established and the functional relationship between the load of the gantry oil cylinder and the scale parameters of the mechanism was set up. Setting the maximum load of the driving oil cylinder of the gantry overturning mechanism as the minimum as the objective function, and using MATLAB to obtain the optimal scale parameters of the gantry overturning mechanism based on the composite optimization algorithm, the optimization of the maximum load of the rear gantry oil cylinder is reduced by about 7.1%. Based on Creo software for rigid body dynamics simulation analysis, the simulation results verify the correctness of the scale optimization model. Based on the optimization results, a prototype was manufactured and subjected to functional testing, which showed good performances and met the requirements for wall panel installation.