In order to determine the pulsed loading parameters in the hydroforming of the reducer, an austenitic 304 stainless steel reducer is taken as an example. The simulation model was established by using finite element analysis (FEA) software. The hydraulic loading speed was 2 MPa/s and the amplitude 3 MPa and 5 MPa, frequency 1 Hz and 05 Hz were combined for loading. Based on the comparison with analysis of the simulation results of the wall thickness distribution of the formed parts, it was found that the maximum thinning rate and the maximum thickening rate of the composite parts were 5 MPa and 1 Hz respectively. The distribution of wall thickness is more uniform. The result of the actual machining proves the feasibility of the above computer aided design (CAD) method.