In order to improve the quality and efficiency of hazelnut shell breaking and optimize the performance index of hazelnut shell breaking machine, the main shell breaking device of this device is knife roller. Through the optimization of the structure parameters of the knife roller, it is found that the shelling rate of the hazelnut sheller is affected by the diameter of the knife roller, the rotation speed of the knife roller and the distance between the knife rollers. The single factor test and orthogonal test are carried out for the above three factors, and the optimal structure parameters of the knife roller are finally determined by using the central combination theory and the simulation data by the design expert software. The results showed that when the rotation speed of the cutter roller was 180 R / min, the diameter of the cutter roller was 181 mm, and the gap between the cutter rollers was 11.2 mm, the shelling rate and kernel breaking rate of hazelnut were 93.35% and 7.69%, respectively.