Abstract: Making the synthetic seismogram is the basis of oil and gas exploration, and it is the bridge connecting geology, well logging and seismic data. In this paper, based on basic principle of synthetic seismogram, combined with the specific case in oil and gas exploration, difference between time-depth relationship of VSP data and the synthetic seismogram, effects of seismic data on making synthetic seismogram and selection of wavelet were analyzed. Finally, the application of synthetic seismogram in oil and gas exploration was elaborated by cases, such as grasping the regional velocity, defining seismic response characteristics of reservoir, identifying the multiple wave in seismic data and eliminating geological "illusion" from seismic data.