For the existing optical wavelet transform were implemented all based on continuous wavelet transform

rather than discrete wavelet transform，its applicability was restricted . To solve this problem

the principle of the optical implementation method of discrete wavelet transform algorithm (Mallat algorithm) utilizing optical 4f system was analyzed

and its optical implementation method was proposed. For SLM(Spatial Light Modulator) can only implement nonnegative real function and CCD can only record light intensity

one design method of optical wavelet filters which were applied to optical 4f system was given. With this kind of optical wavelet filter

the wavelet decomposition in Mallat algorithm was implemented utilizing optical 4f system

and the wavelet reconstruction in Mallat algorithm was implemented by use of numerical computation. Experimental results verify the methods.