Abstract: An approach to construct a 3-band scaling filter and a wavelet filter was proposed,which not only is of orthogonality,symmetry and compact support but also has high vanishing moments.By setting the vanishing moment and switching the orthogonality of the scaling filter,this approach effectively reduces the number of unknown variables during the process of constructing the scaling filter and the complexity of the calculation process.Subsequently,a decomposition scheme of the polyphase matrix with paraunitary property was proposed on the basis of the lattice structure theory.Using this decomposition scheme,the corresponding wavelet filters are constructed whose impulse response length is 9 and vanishing moment is 3 and whose impulse response length is 15 and vanishing moment is 3 or 4,respectively.Finally,multi focus image fusion is implemented by using these wavelet filters.Experimental data show that the fusion result is better by using these 3-band wavelets than by using dyadic wavelets.