Abstract: To improve the adaptability of the traditional bionic legged robots and simplify the control system, a bionic legged robot based on the tensegrity structure is proposed. According to the physiological structure and movement mechanism of the human leg, the equivalent model of the Snelson X-shaped tensegrity structure of the leg is established, and the structural stiffness matching method is given through structural stability and kinematics analyses. The movement of the rotation center of knee joint is achieved by separating the rotation and translation motion, and the dead point of the planar four-bar mechanism is used to lock the knee joint when the robot is standing. The linkage unlocking is achieved through the crank slider mechanism and the displacement amplification mechanism, thereby realizing the rigid-flexible conversion of the knee joint during the walking process of the human leg. Finally, a physical prototype of the single motor driven bionic legged robot is tested to verify the effectiveness and practicability of the proposed structure.