Seismic data acquired in the past has been analyzed in this study to confirm the existence of methane hydrate in southwestern offshore Taiwan and purpose procedures for future methane hydrate exploration. Based on results of reinterpretation of seismic data, seismic characters reflecting methane hydrate distribute extensively in the study area. It is worthwhile to proceed exploration of methane hydrate in the area in the future. Exploration potential of methane is assessed by related area distribution, thickness and porosity of strata containing methane hydrate, and saturation of methane hydrate of pore fluid. Better understanding of these parameters depend on quantitative or qualitative analyses of high quality of seismic data. To accomplish this goal, seismic processing flows were re-designed to avoid interference of multiple. Seismic character analysis, amplitude – offset analysis and analysis of methane hydrate saturation were applied on a high-resolution 160 channels seismic profile. Study results show that high- resolution seismic data are criterion for assessment of exploration of methane hydrate in the future.