A unified multi-modal terrain segmentation and adaptive gait planning method for quadruped robot is proposed to solve the problems of modal uncertainty and lack of continuity in gait switching. The multi-modal terrain segmentation framework is used to enhance the adaptability to different modal combinations, and the Froude number constraint is introduced based on the terrain recognition results to achieve physically continuous gait transition. The experimental results show that the proposed method can maintain robust terrain recognition performance under multiple modal combinations, and significantly improve the stability of gait switching in complex terrain.