Abstract: Abstract: At present, extruding crack and centrifugal shell-breaking methods are adopted as the main strategies for pecan shell-breaking equipment. But the low production rate is hard to be improved. Meanwhile, the bad processing quality will affect the further processing, which restricts the development of the pecan processing industry. To solve such problems, this study proposed a bionic knock method, which imitated the artificial processing to shell pecan, and developed a bionic knock type shell breaker. Design and experiments were both mainly focused on the structure and parameters of the shell breaker. The paper described the overall structure of prototype and introduced the technical parameters of shell breaker, and the three-dimensional model was built by Pro/Engineer software. In this study, cell feed wheel was designed to translate pecan into feed pipe from hopper one by one like water flow, and thus the method could avoid pecans plugging the feed pipe. The bottom of the pipe was linked with shelling system, which was one of the most important parts during the study. In order to figure out a more efficient shelling method, a bionic knock structure was designed based on the particle properties and mechanical behavior of pecan rupturing under knock loading, and the mathematical model of designing the shelling system was built. The system included 3 parts: disk-cam, support point and mechanical arm. The mechanical arm could roll around the support point in a certain angle range, and through the profile curve of disk-cam, the movement of mechanical arm could be controlled to finish shelling process. The groove structure was designed, which could reduce the deformation of pecan under the knock to protect the kernel from damage, and within a few sockets on the inner wall of groove, it could change the surface load into linear load and achieve a better shell-breaking quality. According to the movement requirements of shelling system, the structure dimension of mechanical parts was built, the push movement angle of the cam was optimized by the inverse method and the practical cam profile curve was designed. What was more, the transmission system and the time sequence relationship on all the actions were both introduced, and the transmission system diagram and the one time sequence diagram on shell breaker were showed in the paper. After the physical prototype of mechanism was manufactured, the field test was performed, and 3 groups of pecans were selected. The results showed that the prototype working performance was stable and high-quality. While the rotating speed of camshaft was 52 r/min, the pecan moisture content was set nearly to 14.55%-16.35%, and the diameter volume was from 18 to 22 mm, the shell-breaking rates of the 3 test groups were 99.59%, 99.40% and 99.31% respectively, which were high, and the kernel damage rates were 5.77%, 7.00% and 6.01% respectively, which were low. The processing efficiency was also higher than the traditional shelling equipment, which could reach 95.54, 98.00 and 91.25 kg/h respectively for the 3 groups of pecans. The test performance of prototype could basically meet the production demands. The research can enrich and perfect the mechanism and method for shell-breaking of walnut, and provide the technology and equipment support to realize the mechanization of pecan processing industry.