On the basis of the signal quality standard given by the harmonic analysis method, an quality assessment of grating signal based on wavelet analysis is put forward and its characteristics are discussed. Compared with the harmonic analysis method, wavelet analysis characterize its local excellence both in time and frequency domain for every time of the wavelet transformation, with the wavelet analysis method the transient characteristic of the grating signal can be analyzed more subtly by changing the scale, and all possible noise can be filtered. The most possible approximation of the original signal and the least signal distortion are get with three to five times transformation, the ideal result is then quickly obtained. The corresponding experiment of grating signal quality assessment is given with wavelet analysis.