For controlling a threshing mechanism of a combine harvester parameters of the threshing mechanism are adjusted with respect to a nominal crop throughput determined for corresponding harvesting conditions to an optimal value, the changing automatically and the adjustment includes automatically determining a deviation of an actual crop throughput from the nominal crop throughput, and adjusting at least one threshing mechanism parameter for adaptation to the actual crop throughput; also a combine harvester with the control device for performing the method is proposed.