Abstract: A multilayer approach to the midcourse trajectory design for a surface-to-air missile to maximize the kill probability was presented. Three layers were discussed. The first layer represented the midcourse trajectory of the missile, the second layer represented the terminal homing phase, and the third layer was the warhead damaging process. The first-layer trajectory was optimized with a constraint on the value of pitch angle at the handover point to the terminal phase. The pitch angle was used as the global parameter to combine the first and second layer in generating a field of optimum first-layer midcourse trajectories. The second-layer was a Monte-Carlo terminal homing simulation to get the average and standard deviation of miss distance, which combined the second-layer and the third-layer. The third-layer calculated the missile-s kill probability by using the standard deviation of miss distance. The pitch angle and midcourse which maximizing the kill probability were the optimum results of the system. The multilayer approach demonstrates the connection between the midcourse trajectory design and the kill probability. It allows the kill probability be a measure in the midcourse trajectory optimization. Two cases that intercepting high-attitude-high-speed and low-attitude-low-speed cruising target are presented.