Abstract: The engine often works with dynamic conditions during the tracked vehicle travels on off-road. To improve dynamic performance of the tracked vehicle and to overcome the insufficiency of some shift schedule designed based on engine steady state characteristics, an transmission energy loss model was established for engine in this paper, considering multi-model functions including engine internal power loss, dynamic engine working with torque converter, and the output torque of transmission system in different shifting condition. Moreover, the transmission energy loss model was arranged to compute the drive torque and energy loss for the tracked vehicle under off-road conditions. Compared with energy loss calculation result based on the basic shift rules, the energy loss calculation results according to the modified shift rules show the modified shift strategy can make the tracked vehicle better power efficiency. The proposed transmission dynamic model and energy loss computation model provide an effective tool to study and evaluate the shift strategy of tracked vehicles.