The automatic transmission technology is the key technology of tractor transmission system control,is also an effective way to improve the efficiency of the tractor working.The application status at home and abroad is summarized,and the deeply analysis of transmission system,hydraulic system,control strategy,shift quality control technology of power shift transmission and continuously variable transmission which widespread use on the foreign large and medium power tractors at present are carried out.The development and research direction of automatic control technique of transmission on tractor is forecasted based on the development trend of transmission gearshift control.