An analysis with Fourier series on electric signals of meso-spray process of pulse MIG welding of aluminum shows many harmonic waves of different frequency in the signals,including the inherent high,low frequency elementary waves of short circuit and the harmonic waves from pulse current besides the noise signals of high frequency.The wavelet filtering with adjustable threshold is applied to study and handle the electric signals from meso-spray process of pulse MIG welding of aluminum,displaying a good solution on suppressing the noise in the signals.