Abstract: The Mesozoic in northern South China Sea is characterized by low frequency (mainly in 8~35 Hz) and weak energy in seismic reflectance, so it is difficult to get high signal?to?noise ratio seismic data by using conventional seismic acquisition technology. This paper redesigned a new low?frequency source of 6 400 in3 for improving the energy in low?frequency end, and put the cable sinking depth increased to 18 m for reducing ambient noises the cable received. The comparison results from marine seismic source test showed that by using the combination of such a new low?frequency source and deep sinking cable acquisition, the Mesozoic reflectance obtained is of much higher signal?to?noise ratio than before. Also, this paper presents the main parameters for test and indicates the advantages of this combination in aspects of final migration profile, velocity spectrum and amplitude spectrum