Abstract: Based on the ground information obtained by proximity sensors,it is studied how the foot moves when the leg transfers its supporting point.Amedifled composite cycloid is proposed as the foot trajectory for solving the adaptive gaitproblem over rough terrain. Therefore,the abruptness and the impact betweenfoot and ground may be avoided,and adaptive gaits over rough terrain can be changed into simple periodicgaits,as to simplify the control strategy.