Abstract: The ocean bottom seismograph (OBS) is a new equipment currently used for hydrate seismic exploration in the South China Sea. It is characterized by dense shooting and sparse receivers, which leads to narrow illumination of reflection wave in the shallow area. In the performance, the down-going and up-going waves share same wave source, and the down-going wave passes a longer distance, therefore, it may effectively solve the problem of narrow illumination and improve imaging accuracy. In this article, a reasonable de-bubble operator is designed for suppress of serious bubble of the P component; then the wave fields are separated by the dual-sensor summation; and finally the down-going wave data are processed and good imaging results gained. Moreover, the final imaging data is rich in low-frequency information, which can effectively make up for the low-frequency information missing in conventional towing cables and facilitate subsequent reservoir inversion studies.