Due to the complex and changeable operating environment of the highpower tractor, the densely arranged gears of the power shift transmission (PST) or field random load fluctuations could easily lead to frequent and random shifts, destroying the stability of the working conditions and affecting the performance and operating quality. Therefore, to solve the problem caused by random load fluctuations during tractor operation, a shift strategy by the adaptive correction of random loads was proposed. Firstly, the throttle opening, slip rate and vehicle speed were chosen as the control parameters to calculate the theoretical shift schedule of PST. Then, three correction parameters such as random load variation coefficient, throttle opening change and steadystate load change were introduced to calculate the shift correction under random load fluctuations through fuzzy rules. Combined with the convergent shift delay strategy, the light load or the transportation condition adopted the theoretical downshift law, and the heavy-duty operation adopted the adaptive upshift delay, the larger the load fluctuation was, the larger the upshift delay was. In addition, a high-power tractor hardware-in-the-loop simulation platform for the test of the gearbox control system was designed and developed. The tractor transmission system model based on AMESim and Simulink was used to test the performance of the transmission control system under different operating conditions. The simulation results showed that under road transportation and plowing conditions, the shift times of the proposed shift strategy were 63.16% and 45% lower than that of the traditional shift strategy, respectively, and the fuel consumption of the proposed shift strategy were 0.76kg and 0.47kg, which were 0.51% and 1.03% lower than that of the traditional control strategy, respectively. The strategy could effectively suppress frequent random shifts caused by random load fluctuations and balance the power and fuel economy of the tractor.