Abstract: When driving a tractor in the field, the operating strength and the physiological load of an operator differ greatly from the steering mechanisms. The number of heart beat and the volume of the oxygen consumption were tested based on the two different steering mechanisms. Then the rule of psychological and physiological changes with the different steering mechanisms was achieved. The results state that the operating load for volunteers with the different age and driving age varies from the different steering mechanisms. It provides data of operators themselves for designing the each system on a new model and supplies the important theoretical reference to revising the existing system on tractor.