Abstract: Many scholars all over the world have been studying tractor-implement combination on auto-control for decades. But so far most of studies focus on its sub-systems such as engine control system, suspension control system, plough resistance control system. Studies on the whole units integrated control were seldom reported. Tractor-implement combination is a complicated non-linearity and inertial control system. There are couple relations among system parameters. So it is difficult to build an exact mathematic model for integrated control of the tractor unit. A simulated model of the tractor unit based on three parameters such as engine load rate, drive wheel slip and tillage resistance was proposed by studying the unit dynamic characteristics in this paper. This model uses fuzzy control theory to realize integrated control of the tractor unit. The experiment showed that this control model was able to automatically infer output control signals such as gear, throttle or plough depth according to tillage resistance. These signals were sent to the control implement unit to control transmission, throttle or plough depth of implement. So it simulated driver to control tractor-implement combination by computer. The computer integration control was able to make engine work on higher engine load rate and lower specific fuel consumption. The control effect was better than the ones by manual control. And the experiment by computer control was able to be repeated and the test result can be compared with. So this method provides a definite practical reference for integrated auto-control of tractor-implement combination.