Abstract: A ground mobile robot which adopts wheel-leg-track compound moving mechanism is studied.Firstly,two kinds of obstacle-negotiation processes are described respectively,i.e.leg-track and wheel-leg-track compound obstacle negotiation.The dynamic modeling for process of leg-track compound obstacle negotiation is built.The relationship between motor driving torque and robot velocity,and relationship between motor driving torque and obstacle height are analyzed.The theoretical foundation to ensure adaptability of robot in complicated environment is provided.