Aimed at the requirement of quick and accurate dynamic weighing, combining the characteristic of digital filter about wavelet, applying fast Mallat decomposing and constructing algorithm, a new signal processing method of dynamic weighing by discrete wavelet transform was discussed. The results of quantitative feeding dynamic weighing show that the stable time of the constructed low frequency parts is 0.128 s after wavelet decomposing wiped off high frequency parts. The error of signal construction is -1.5%～2％. The signal processing of dynamic weighing by wavelet transform can reflect the actual wei ght of material more quickly and more exactly than that by the Fourier transform. 