Abstract: In view of the current state that the crawler-type vertical axial flow combine harvester can not be quickly converted between different crops, small radius steering is easy to cause surface soil damage, non-differential threshing drum is not suitable for high yield crop threshing, and without anti vibration water treatment the screen surface can not adapt to the cleaning processing of the crop with high water content, the loss rate of the cutting table is high, the threshing separation ability is poor, and the power consumption is high, we have improved the design and experiment of the main working parts such as cutting, threshing, cleaning and walking parts. The cutting table was designed to be a stepless speed adjustable telescopic structure, the threshing device was designed to be a longitudinal-axis roller with the same diameter and different speed, and a single HST (hydro static transmission) in situ steering walking device and an anti adhesion cleaning device were adopted. The results of laboratory tests and field tests showed that: The retractable cutting table could realize the fast conversion between the rice/wheat harvest state and the rape harvest state, and enlarge the use function of the cutting table; the loss of rapeseed was significantly reduced, and compared with the conventional method, the loss rate of rape was reduced by 2.8 percentage point. The threshing and separating device with the same diameter and differential speed could make use of the different speed of the threshing cylinder, and the threshing effect and separation ability were improved at the same time. Compared with the equal length single speed axial flow roller, the net loss rate of entrainment and removal decreased by 0.02 percentage point and 0.09 percentage point respectively, and the crushing rate was reduced by 0.017 percentage point. When the steering wheel was turned to a single side in wet field, the brake track was dragged on the surface of the ground, and the mud was accumulated. However, when a single hydraulic motor was used to steer the transmission, the steering would not occur. The conventional steering mechanism realized the steering with one side of the track brake, and consumed the braking power considerably; the in-situ steering had no braking, and both sides of the track were reversed. In-situ steering mechanism reduced surface soil damage and steering power consumption, and the power consumption was reduced by 37% when the steering was replaced by the single side. Cleaning mechanism and cleaning sieve after water repellent treatment shook board surface, which improved wet grain cleaning performance, and the loss rate was reduced by 0.9 percentage point and the impurity rate was reduced by 0.4 percentage point. The improved design of the main working equipment of the combine harvester improves the working performance of the whole machine.