In the field of intelligent manufacturing and construction, the problem of robot energy consumption is prominent, and it is an urgent issue to effectively reduce the energy consumption of robots when performing tasks. In view of the shortcomings of traditional trajectory optimization methods, this paper utilized the NSGA-II algorithm to study the trajectory planning of a plate-mounting robot with high load and low energy consumption. Firstly, the kinematics and simplified rigid body dynamics of the building slabstone-installing robot are analyzed. Secondly, aiming at the stability, efficiency, and energy consumption of the robot, the NSGA-II is used to optimize the trajectory of the robot in the no-load state and the load state of 200 kg, respectively. Furthermore, this paper introduces an evaluation method (quality-efficiency optimization method) to select the best result based on quality and efficiency standards, and selects the optimal solution while ensuring the diversity of algorithms. Finally, the simulation and experimental results show that this method can effectively improve the load capacity of the robot, reduce the overall energy consumption, and maximize the practicality and economy of the optimization results. The energy consumption optimization effect at a load of 200 kg is 14.23%. The research findings presented in this paper lay a theoretical foundation for robot trajectory planning aimed at improving load capacity and reducing energy consumption.