Aiming at signal distortion of milling force and vibration during milling process of splicing dies for automobile cover panel, the empirical mode decomposition(EMD) method combined with wavelet threshold denoising method is used to denoise the cutting signal. The time-frequency domain analysis is carried out on the vibration signal after noise reduction. The influence of different cutting parameters and cutting feed direction on milling splicing die is studied. The conclusion is that when milling direction from high hardness material to low hardness material and the path of cutting is 30°to the mosaic seams, the variation value of milling force is smaller. The abrupt changes of cutting force and vibration amplitude in x, y and z directions are positively correlated with axial cutting depth and feed rate, but are not linear with the cutting speed.