According to the problems of low shell breaking rate and whole kernel rate caused by exerting two forces, a four forces shell creaking machine was designed and made. The contrast shell breaking experiment of ‘two forces and four forces’ and preliminary test were conducted, which showed the four forces shell breaking machine that apply to all over the size of walnuts had a better result than the two forces machine. The extrusion length has a significant impact on the shell cracking situation, but less on the walnut size. With the moisture content 10%, extrusion length 6 mm , cracking effect was the best, and the shell creaking rate and whole kernels rate were 100% and 96.8%, respectively.