To improve the flexibility of the pneumatic hexapod robot,the legs of hexapod robot were driven by trimuscle pneumatic space bending flex joints.The leg was equipped with lifting mechanism,which could change the lifting height of the leg and adjust the height of the center of gravity of the robot.The lifting height and step distance model of robot leg were built.3D motion capture system was used to acquire the lifting height of robot leg,joint deformation and foot working space,and the obstacle crossing height of the hexapod robot was analyzed.The calculation and experiments show that the motions of legs are flexible and the robot can pass through the barrier with 30 mm height.The achieved results provide references to the gait planning and control.