Abstract: Temperature rise optimization design of space manipulator electromagnetic brake coil is done, using a new method which combines genetic algorithm with penalty function. Firstly, optimization model of space manipulator electromagnetic brake coil is obtained with the objective of temperature rise, which considers the restrictions such as electromagnetic force, current and magnetic density. Then, a method combining penalty function with genetic algorithm is proposed to solve the nonlinearity of constraint conditions in optimization model. The method is suitable for global optimization, and guarantees that the solution is always feasible in whole calculation process. The optimization result demonstrates that temperature rise is reduced remarkably. Finally, the brake is put into thermal vacuum environment simulation equipment and temperature rise curve is drawn. The temperature rise measured in the experiment closely meets the objective obtained by the optimization calculation, and this experimental result verifies the correctness of the method and the design.