The vertical distribution feature and diurnal variation of sound scattering layers in the South China Sea were analyzed with the data obtained by the ship-board ADCP and LADCP during an autumn cruise of the ROSE(Responses of Marine Hazards to Climate Change in the Western Pacific)project in 2012.The scatterers in the scattering layer were categorized by the estimates of their vertical speeds.The measurements showed the existence of two sound scattering layers at two depths,0~200m and 300~500m.Significant diurnal variation was observed in the shallower scattering layer,with weak strength in daytime and strong in nighttime.While this diurnal variation was reversed in the deeper counterpart,with strong strength in daytime and weak in nighttime.The vertical moving velocities of the scatterers were also estimated, with an ascending velocity of around 1.74cm/s at nightfall and a descending velocity of around 1.39cm/s before dawn.The analysis also showed that the measurements made by ADCP and LADCP could well complement each other,which benefits the study on sound scattering layer.