Considering the safety threats posed by the complicated topography on the asteroid surface, a dynamic planning method for topography-adaptive landing trajectory is proposed. In this paper, a multi-objective optimal waypoint sequence is developed for the landing process. Based on the hazard detection information, an online evaluation of the collision threats is carried out. To solve the conflicts between hazards and the nominal trajectory, a minimum waypoint re-planning method is designed, which realizes an autonomous switch between waypoint robust tracking and dynamic planning of the local hazard avoidance trajectory during descent. By employing the proposed method, adaptability to the complex topography environment of the lander is enhanced and the asteroid landing mission safety is improved.