Abstract: An ocean bottom seismic survey (OBS) was carried out in the Okinawa Trough of the East China Sea for the purpose to reveal the structure and properties of the crust. Basic principles, structures and survey methods of OBS were briefly introduced in the paper. This is the first deep geophysical exploration ever carried out in the trough using the large capacity air-gun array as seismic source. A survey line was put on the bottom along the direction of NNW-SSE, perpendicular to the structural direction. A total of forty seismometers were placed, of which thirty six were reclaimed successfully. Deep seismic data has efficiently obtained in the test including the multiple seismic phases of Pg, PmP and Pn. It is indeed a successful demonstration of deep exploration for the first time in the Okinawa Trough of East China Sea, which effectively filled the gaps in the deep seismic survey and laid a solid foundation for solving deep geological problems in the region.