This paper analyzed the method of superimposing Moire,Fourier transform Moire,scanning Moire and phase shifted scanning Moire in terms of frequency spectrum.Fourier description of several Moire contoure methods is presented .The relation of these method in frequency domain is dicussed.The essential characterstic of these methods is that fundamental frequency which carries Moire information is shifted to the oringin in order to obtain Moire fringe.