A walnut shelling machine with functions of shell crushing, kernel taking and shellkernel separating was designed, which could increase the shellbroken rate and kernelunbroken rate. However, the problems of incomplete brokenshell and unhulling crushedshell were also remained. Thus, the flexiblebelt 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 20mm and the critical external force for crack extension was 191N, the cracks could be further extended. Onefactor 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 kernelbreaking rate and kernelunseen rate, A＞C＞B. When the top and low section belt spacing was 14mm, top and low section speed difference was 0.19m/s and upper belt tension was 231N, the hulling effect was optimal(hulling rate was 98% and kernelunbroken rate was 93.7%).