In this paper, a new type of biped mobile robot is designed. Each leg of the robot is a 6 degree-of-freedom (DOF) parallel mechanism, and each leg has three relatively fixed landing points. The leg’s structure gives the robot better performance on large carrying capacity, strong environmental adaptability and fast moving speed simultaneously. At the same time, it helps the robot move more steadily and change direction more simply. Based on the structural features of the leg, the inverse kinematics model of the biped robot is established and a unified formula is obtained. According to an analysis of robot’s workspace, gait planning is completed and simulated. Finally, the special case that the robot can keep the upper body horizontal while walking on a slopy surface is validated.