Abstract: Multi-frequency in situ sediment seabed acoustic measurement system is produced by Second Institute of Oceanography,SOA.Utilizing the equivalent circuit of source transducer,analyze the relation between the input pulse and the out pulse of the source transducer.Equal the low frequency source to spherical source with some radius and confirm the resonance angular frequency and the quality factor of the output circus of the transducer with 15 kHz frequency in seawater.Calculate the theoretical received output pulse and the result indicate that the output pulse is not a replica of the input pulse.And compare the theoretical pulse and the practical pulse and find they match perfect in detail.And this indicates that the parameters of the source resonance the paper ensured represent the source resonance of the system very well.