Abstract:A walnut shelling machine with functions of shell crushing, kernel taking and shellkernel separating was designed, which could increase the shellbroken rate and kernelunbroken rate. However, the problems of incomplete brokenshell and unhulling crushedshell were also remained. Thus, the flexiblebelt and differential velocity extrusion system was used to make the walnut kernel out and the effect of that operation was analyzed. The results showed that when the mean crack length was 20mm and the critical external force for crack extension was 191N, the cracks could be further extended. Onefactor test was carried out to explore the influences of the top and low section belt spacing (A), top and low section speed difference (B) and upper belt tension (C) on hulling, and the orthogonal experiment was carried out to analyze the influence of the above three factors. According to the experimental results, the influences on the first grade kernel rate and the second grade kernel rate were C>A>B, and for kernelbreaking rate and kernelunseen rate, A>C>B. When the top and low section belt spacing was 14mm, top and low section speed difference was 0.19m/s and upper belt tension was 231N, the hulling effect was optimal(hulling rate was 98% and kernelunbroken rate was 93.7%).