For resolving the question of dynamic scheduling of flexible shop dynamic scheduling method based on genetic algorithm is put forward. A math model and objective function for dynamic scheduling of flexible job shop is set up by analyzing problem of flexible job shop scheduling. A genetic operator that can meet the need of production scheduling of flexible job shop is designed based on working procedure coding. Coding, crossover, mutation, fitness calculation, controls parameter selection and stop condition are studied. According to designed algorithm, the simulation of dynamic scheduling of flexible job shop is done. Results of the simulation prove correctness of the study.