Abstract: The Xiashu loess deposits from Tutang section with the character of less grain size change in northern part of Jiangxi Province, was measured by four laser particle size analyzers, i. e., Mastersizer-2000, Bettersize-2000, HoribaLA-950 and LS-13320, to identify the differences among the grain size of Xiashu loess and their impact on the research results and conclusions. The testing results indicated that the difference among silt fraction measured by the four instruments is minimal, but the differences among sand and clay measures are maximal, which suggests that the laser analysis of grain size is most suitable for the determination of silt particle size range. Based on some statistical parameters and methods, for example, grain-size frequency curves, probability cumulative curves, grain-size components, C-M diagram, scatter plots of grain-size parameters and vertical change of grain-size parameters on profile, the measured results from the four instruments showed some differences in all aspects. The differences among probability cumulative curves, scatter plots of grain-size parameters and thus the vertical change of grain-size parameters on profile are large, which might after the judgment of the researcher and result in different research results.