Abstract: Researches were carried out for the lack of theoretical analysis of shift quality of current shift control for AT. First a transient dynamic model of AT was built. Then taking the power train of heavy-duty off-road vehicle as an example, an evaluation method with shift jerk and slipping work was presented to analyze the characteristic of torque phase and inertia phase in the ascending shift process. The analysis results show that the minimum time MAP of torque phase and the concave trajectory of turbine speed in inertia phase can help to improve shift quality. Following the corresponding phased control strategy was proposed. Simulation and real vehicle test results verify the correctness of quality analysis method, and show that it can improve the shift quality for AT.