Abstract: Temporal and spatial variations of nearbed suspended sediment play a crucial role in understanding the erosion and deposition process of estuarine topography. For a long time， most observed data of the nearbed suspended sediment concentration （SSC） in estuary are acquired based on a single point observation or by water sample treatment，i.e. the traditional layout method of instruments （TLMI） . Here， an accuracy of applying Argus Surface Meter IV （ASM-IV） is studied based on the near bed SSC measurements of South Passage of the Changjiang Estuary in sequent of 20 tidal cycles. The results were drawn as followed: (1) Compared with the SSC from ASMIV， the relative error of measured SSC resulting from TLMI during spring tide period was larger than those at middle and neap tide periods， with corresponding values of 24.15%， 17.31% and 16.28%， respectively， and the relative error by TLMI increased from above 52 cm to the bottom. (2) Compared with those by ASM-IV， the measured suspended sediment flux by TLMI was usually underestimated. (3） During spring tide period， nearbed vertical SSC within 1 meter to the bottom showed a relative uniform distribution， while conspicuous stratification occurred during the middle and neap tide periods. The points of largest difference between measured data by ASMIV and the averaged SSC within 1 meter to the near bottom were located from 20 cm to 50 cm above the bottom. Thereafter， it can be indicated that ASM-IV is more suitable to estimate the nearbed SSC at spring tide or at location closed to the bed. The SSC of 0.8H at the depth profile is more accurate than the bottoms SSC by TLMI during middle or neap tide period．