The invention discloses an optimization design method of a rail transit vehicle noise digital prototype, and relates to the technical field of rail transit. According to the optimization design method, through establishing an acoustic geometric model consistent with the geometric dimension and noise of a real vehicle, the sound power of each noise source and the sound insulation quantity of each sound insulation part are used as design variables. Under the constraint conditions of the total weight of the vehicle body, the total design cost and the noise under each working condition are met, anNCGA algorithm is adopted to carry out optimization solution on noise under each working condition to obtain an optimal solution of the noise under each working condition, and the whole modeling andoptimization solution process can be realized through a software program, so that the modeling difficulty and time consumption are reduced, the complexity of optimization calculation is reduced, and the optimization efficiency is improved. The design variable and the optimization variable corresponding to the optimal solution are used for guiding the noise design of the whole vehicle, constraint conditions are met, the design of the whole vehicle is economical and practical, and the noise set value of the whole vehicle is optimal.