Aiming at the complex ground environment,lots of steps and wooden obstacles,a kind of mobile robot which was compounded leg and track was designed.Based on the analysis of the bone structure parameters and movement characteristics of the canine leg bones,the mobile robot leg structure with the 3-joints configuration and the track composite was designed.To reduce the quality of the whole machine as much as possible,the track parts and the thigh structure of the robot leg were organically compounded.The kinematic model of the robot single leg was constructed,and the robot foot working space was analyzed.The forest obstacle crossing strategy for the leg-track compounded mobile robot was proposed.The dynamic characteristics of the robot joints were simulated.The simulation results show that the use of leg joints swing and track propulsion combination and timely switch,the leg-track compounded mobile robot can achieve steps and fall tree obstacles overbarrier flexibly;in the process of obstacle crossing,the joint torque of the leg changes smoothly except for the abrupt change of the joint torque at the moment of contact with the obstacle;track movement mode and foot movement mode switch smoothly.It is the technical base for the robot prototype and control system development.