Abstract: Genetic algorithm is a kind of search and optimization method which based on the life-evolution mechanism, and it can be used to solve complex optimization problems for its peculiarity of the global optimum and the implied parallel. This paper took straw-mulching cutlass as study object which was the main working part of the whole rice straw returning machine, and its force analysis was carried out. The optimization model of power loss was established by taking cutter slices combination parameters as design variable, and the optimization method based on genetic algorithm was developed. Results showed that the minimum power loss of cutter slices was 5.12 kW. The validation experiments verified that the minimum power loss was 5.5305 kW under the conditions of optimum parameter combination, which accorded with optimization results. The optimization method is feasible, which can provide theoretical reference for the whole machine optimization.