At present, it is universally acknowledged that the mechanical shell-breaking method is regarded as the main research strategies in the process of pecan shell-breaking equipment design. The design and improvement of shell-breaking method and principle had been studied extensively. However, in each kind of shell-breaking method, the research on the loading contact form between the broken shell mechanism and the pecan was neglected. Whether in the study of pecan shell-breaking principle and method or the design of mechanical equipment, the load which was provided with a single contact form was bore for pecan, such as point load or line load. In the course of processing, the size of the shell-breaking force was prone to cause the partial breakage of the shell or the serious damage of the nut, which led to the phenomenon of low shell-breaking rate and high nut damage rate. Therefore, the groove shape hammerhead with sockets was developed. The hammerhead structures of different loading contact form were designed. And the shell-breaking effect on different loading contact form was researched by test. When the pecan was broken, the shell-breaking rate, nut damage rate and exposure nut rate of pecan were deemed as evaluation index. The crack distributions which were formed of three hammerheads in different loading directions were compared and analyzed. The finite element analysis software Abaqus was used to research the distribution and propagation of crack in the process of the shell-breaking, which considered the structure of the hammerhead with four different numbers of sockets as the variable. The orthogonal test which considered the structure parameters of the hammerhead and the loading direction as experimental factors was designed and used to determine the optimum combination. The results showed that the structure of the hammerhead in the groove shape can reduce the influence of the loading direction factor on the shell-breaking effect. Containing a plurality of sockets can make the pecan shell generate a large number of local crack points which extended along the tangent line of the socket to produce and extend crack. This structure can act as a crack guide. With the increase of number of sockets, the crack distribution of the pecan shell was uniform and the range was wide. This structure can improve the quality of shell-breaking. When the groove diameter was 28mm, the number of sockets was 7, the most satisfactory shell-breaking effects were obtained, which generated the shell-breaking rate of 98.88%, the first grade nut rate of 37.05%, the second grade nut rate of 57.24%, and the nut damage rate of 5.71%.