Abstract:Because seismic wave is excited in well(open or cased well),a part of excited energy propagates along the fluid column in the well with tube wave mode,which causes complex tube wave pattern on original cross-well seismic records.There are three different propagation mechanisms of tube wave,to be found during cross-well seismic work in a north prospecting area of china:①tube wave in source well(diffraction);②tube wave in receiver well(body wave);③tube wave in source well-guide wave(tube wave in receiver well).Using theory of well coupling to analyze the wave propagation mechanism.in the paper and these mechanisms Have been proved by synthetic records.All tube waves exited from source have close relation to secondary source in hole.The tube wave both has advantages and disadvantages.Studying producing mechanism of tube wave and its propagation mode and interpreting tube wave on cross-well records can use tube wave to get some information on stratum or lithology.