In order to solve the problems of high labor intensity, low production efficiency and low degree of mechanization in hilly and mountainous orchards, a power chassis for hilly and mountainous orchards with hydraulic control and mechanical transmission was designed. According to the working requirements of the power chassis of the hilly and mountainous orchards, the key components of the power chassis such as hydro static transmission (HST), suspension lifting device and hydraulic drive system were designed and matched, the hydraulic system model was established by using AMESim simulation software, the structural design and simulation analysis of the hydraulic system were carried out, and the motor speed of the system was determined to be 129r/min and the motor displacement was 35.2L/min, the displacement of the front and rear pumps of the duplex pump was 10mL/r and 6mL/r, respectively, and the working pressure was 25MPa. The performance test of the whole machine was carried out. The performance test results of the whole machine showed that the straight-line driving offset rate of the power chassis was 1.9%, which met the requirements of the corresponding national standard (≤6%). The walking speed of the whole machine was 5km/h, the minimum turning radius was 1.08m, the maximum climbing angle was 27°, the maximum lifting angle of the mounted tool was 30°, the response speed of the rear suspension device was 1s, and the steering performance of the power chassis was good, which can adapt to the narrow slope working environment of hilly and mountainous orchards. When the rotary tiller was mounted for rotary tillage operation, the stability coefficient of tillage width and tillage depth were 98.9% and 96.4%, respectively, which met the requirements of the national standard (≥85%). The hydraulic control system of the crawler chassis of hilly and mountainous orchards conformed to the design standards of crawler tractors for mountainous orchards, which can provide a reference for the development of power chassis for hilly and mountainous orchards.