The state-of-the-art of hydraulically automatic transmission is analyzed from the aspects of improving performance

transmission efficiency

and shift quality.And the research progress of shift quality enhancement by shortening the time of power interruption and reducing shift jerk for mechanical automated manual transmission is analyzed from the standpoints of structural refinement of power-train

improvement and optimization of actuator and integrated control during gear-shifting process.The technical feature and current situation of dual clutch transmission are also introduced.Furthermore

the up-to-date progresses of continuously variable transmission in reduction of power loss

improvement of transmission efficiency

enlargement of torque capacity

as well as maximization of user acceptance are analyzed.Finally

the development trend of automatic transmission technology is prospected.