In order to solve the problem of lack of special cutting and beating machinery for King grass, the integrated process of King grass cutting and beating was studied, and a small combined King grass cutting and beating machine for family farmers was designed, which met the diversified requirements of King grass processing, and improved the quality of King grass cutting and beating machine working performance. Through theoretical analysis, the structure design and parameter calculation of the key parts such as feeding device, cutter and throwing board were completed. The cutting process of cutter mechanism was simulated by ANSYS/LS-DYNA. According to the orthogonal test, the main and secondary factors affecting cutting power consumption were cutter type, clearance between moving and fixed cutter, fixed cutter height. The notched circular cutter was selected, the clearance between moving and fixed cutter was 2mm, and the height of fixed cutter was 23mm. Through the processing of the prototype and the optimization test of King grass beating, the optimal structure and working parameters of beating process were determined as the spindle speed of 1400r/min, the King grass crushing mode was standard hammer and toothed plate crushing, and the slurry discharge structure was round hole concave plate. On the basis of experimental research, the small King grass chopping and beating machine was improved. The results of the improved performance test showed that the pure working time productivity of King grass cutting was 545kg/h, and the standard grass length rate was 86%;the pure working time productivity of beating was 150kg/h, and the long grass content in pulp was 9.1%.