Based on the analysis of a large number of data, where the suspended sediment concentration was taken as the research object, it wasfound that the limits of that the two kinds of the common instantaneous samplers, including the acquisition point, could not be accurately controlledand the samples could not be completely sealed. The limits are the key factors that leads to the low correlation coefficient between the turbidityvalue measured by the turbidity meter and concentration of the on-site collected water. In the complex flow region, the influence of the traditionalinstantaneous sampler’s limits could be significantly enlarged. It is suggested that the precision of the instrument and calibration sampleshould be paid attention to when the samples are collected and processed.