A multi-mode hydraulic steering system based on PID control algorithm was designed to improve the maneuverability and efficiency of high clearance sprayer. The new technical scheme of the hydraulic system was proposed. The coupling model of mechanical-hydraulic system was established in AMESim software, and the optimal combination of PID parameters was determined by sequential quadratic combination optimization algorithm. And then the control precision of the system was simulated under different load force and load mass. The simulation results showed that the controlling precision was superior when the proportional coefficient was 19.087, the integral time constant was 2.008, and the differential time constant was 0.032. When the loading force difference or the load mass of the front and rear hydraulic cylinders was increased, the displacement error was increased, and the maximum error was only -2.18mm, which meant that the PID control algorithm and pressure compensation system can ensure the control accuracy. The multi-mode hydraulic steering system was developed for sloping road and field experiment. For the field experiment, the average displacement error between steering cylinders of front and rear wheels was 4.07mm, and the maximum displacement error was -17.59mm. For the sloping road experiment, the average displacement error between steering hydraulic cylinders of front and rear wheels was 4.89mm, and the maximum displacement error was 21.34mm. The measured value of steering radius at different steering angles was a little greater than the theoretical value for both steering modes and the error rate was less than 4.0%. The experimental results showed that the designed steering system had superior control accuracy and stability.