Abstract:How to determine the seismic wavelet at up-hole trace from seismic data and logging data is the key of wave impedance of formation at uphole trace.On the basis of detailed studying the method of determining seismic wavelet's length proposed by Mr.Rietsch,the paper presented a method for fine picking the seismic wavelet at uphole trace based on discrete inversion theory and considering spatial variation of wavelet:1.the amplitude spec-trum of preliminary wavelet is picked up from mul-ti-channel correlation method;2.phase spectrum of preliminary wavelet is determined combining with logging data;3.finely resolving seismic wavelet at uphole trace by iterative computation based on dis-crete inversion theory.