A set of hydraulic drive system with series-parallel combined double pumps and motors was designed to solve the problems of many moving parts and a long mechanical power transmission line of traditional rapeseed combine harvester. The system was applied in 4LYZ-1.8 rapeseed combine harvester. The relationship between throttle position and rotate speed was determined with testing hydraulic system. Orthogonal experiments were performed to study effects of header speed,cylinder speed,throwing machine speed and the speed of forced feeding roller on the power consumption of load sensitive system. The power consumption of circuits with main components was measured based on the experiment of power analysis. Results of analyzing variance of orthogonal experiments showed that power consumption of load sensitive system was significantly sensitive to the speed of threshing cylinder. The speed of cyclone separation tube inlet and the speed of header significantly affected the power consumption. Results of analyzing power consumption of hydraulic circuit showed that when the average feed rate was 1.5 kg/s,the average power consumption of five concerned parts including header,forcible feed rotor,threshing cylinder,throwing machine (conveying appliance was belonged) and fan was 1.68 kW,1.00 kW,5.11 kW 2.28 kW and 1.80 kW,respectively. Results of the field experiment of rapeseed combine harvester conducted in Huazhong Agricultural University indicated that the hydraulic drive system constructed can meet the working demand of rapeseed combine harvester,realize the regulation of stepless speed,and adapt different operation conditions. This study can simplify the structure of transmission system for rapeseed combine harvester and offer the reference for the power distribution of different components.