Abstract: In the near-Earth asteroid impact mission, the combination of one impacting probe and one accompanying probe can greatly improve the efficiency of impact effect evaluation. Moreover, if the impacting probe and accompanying probe can be launched simultaneously through one rocket, the mission efficiency will be further improved. At present, there is relatively little research on trajectory co-optimization for this problem, but it is the key to the design of the one-launch-vehicle-two-probes mission. In this paper, a trajectory co-optimization model for the one-launch-vehicle-two-probes mission is proposed. With the minimum of the weighted velocity increment of the two vehicles as the optimization goal, the optimization framework for the trajectory of one-launch-vehicle-two-probes mission is given. Constraints such as launch C₃, the impact relative velocity, and the impact sun angle are considered. The impact probe can use two transfer forms, one is direct transfer and the other is Earth flyby. This paper has optimized 15 candidate asteroids in the 2025 window and provided feasible engineering design solutions. The results can provide theoretical reference for China's asteroid defense mission.