A hydraulic system for small multi-function chassis was designed to be used in the hilly and mountainous regions of southwestern China after a full consideration of the characteristics of the terrain and the relay intercropping in this area. The selection of hydraulic components was determined by a theoretical calculation. A complete hydraulic drive system was adopted in the design to effectively reduce the size and weight,and to realize the stepless speed change and the pivot turn,which effectively solves the problem caused by the small space in the intercropping fields.Climbing experiments show that the machine can smoothly run through slopes less than 25°. All these prove that this machine can meet the basic requirement of walking operation in the southwest hilly areas.