To test and evaluate tracked vehicle power performance, a test bed with load unit is constructed. In order to load vehicle on test bed exactly as same as load on real road, tracked vehicle equivalent inertia to its drive wheel was deduced for modeling vehicle with speed response to its input torque. To system control, strategy of speed tracking combining with disturbance observer was proposed. In the process of speed tracking, single side speed close-loop both sides load was used for less computation and small step time, the validation and precision of design approach was proved by test result.