The invention discloses a threshing method of a threshing device in a grain combine harvester. The threshing method comprises the steps that feeding amount information, crop moisture content information and cleaned grain breakage rate information in the threshing process of the threshing device are collected in real time; according to the collected information, the optimal rotating speed of a threshing roller in the threshing device and the optimal threshing gap of the threshing device are calculated through a fuzzy judgment algorithm; and the rotating speed of the threshing cylinder is adjust...
