Macadamia nuts have been successfully cultivated as crops in Australia and the USA and were introduced to China for experimental planting since 1980s. It is rich in fat and protein. The current production is over 700000 tons annually in China, but processing technology for macadamia nuts is undeveloped, especially breaking shell. So it has important significance to optimize technical parameters of breaking macadamia nut shell. Orthogonal design was carried out for optimizing technical parameters of breaking macadamia nut shell. The loading rate, the loading direction and the moisture content of macadamia nut shell were selected as factors and the integrated kernel rate of macadamia nuts was selected as evaluation index in this experiment. Macadamia nuts with different moisture content were selected as test samples, the moisture content of which was obtained by hot air drying at 55℃. Experiment of breaking macadamia nut was carried out in electronic tensile testing machine. The results indicated that the moisture content of macadamia nut shell and the loading direction had more significant effect on the integrated kernel rate than the loading rate. The most optimal combination of technics parameters was that loading rate, loading direction and moisture content of macadamia nut shell were 45 mm/min, horizontal, and 6%-9%, respectively. In this case, the highest integrated kernel rate of macadamia nut was 93%. The compression test was carried out in the macadamia nut shell moisture content of 6%-9% and the loading rate of 45 mm/min. Average shelled forces were 1018, 2274 and 1173 N in hilum, width and horizontal, respectively. The elastic moduli of macadamia nut shell calculated by the Hertz contact stress theory were 32.24, 68.63 and 39.65 MPa in hilum, width and horizontal, respectively. The results indicated that macadamia nut was anisotropic. Compression capability was the strongest in width and the weakest in horizontal. The shape of macadamia nut was close to sphere. The width diameter was near to average diameter of macadamia nut. The thickness was 4.03-4.36 mm at top of macadamia nut and 2.22-2.48 mm at the middle. That showed that the shell thickness of macadamia nut was nonuniform. The shell's material was similar to wood, so poisson's ratio was near to 0.3. Material properties and geometric model of macadamia nut were imported into ANSYS workbench. The distribution of stress and strain of breaking shell of macadamia nut was obtained by finite element analysis of macadamia nut. According to the finite element analysis diagram of macadamia nuts in the 3 loading directions, it could be known that cracks were easy to emerge and expand in horizontal. It was also horizontal which was the most appropriate for breaking macadamia nut shell. The simulation results were consistent with the results of experiment. The biggest shelled force was 2016 N in horizontal, and therefore the shelled force should not be less than 2500 N for ensuring that all nuts would be cracked. The loaded force should be in horizontal when macadamia nut shell was crushed. It provides the design basis for the macadamia nut shell-breaking machine.