Variable universe fuzzy controller was designed for guaranteeing the quality of full hydraulic steering control on Dongfanghong-LX854 tractor. The basis fuzzy controller was designed according to the characteristics of the system. The optimal basis fuzzy control parameters under different waveforms and amplitude excitation signals were obtained by using rotation up optimization method in Simulink software. The adaptive fuzzy controller parameter turning changed the system to be an optimal control system by adjusting the universe in the basis fuzzy controller according to simulation results. The windowed Fourier transform and self convolution were used to design online identification system. The experiment results on the Dongfanghong-LX854 tractor indicated that the variable universe fuzzy controller was better than the invariable universe fuzzy controller. The measured 20° step response indicated that the regulation time was 2s, the largest steady error was 0.18°, and the response without steady state oscillation. The measured sine response showed that the average delay was 0.3s. The variable universe fuzzy control system lays a foundation for 2BFQ-6 precision planter navigation.