Sanhe, located in the eastern part of the Beijing plain, belongs to the Dachang Depression, and the Late Quaternary strata are fully developed. The sedimentary characteristics of Quaternary deposits mostly rely on qualitative analysis, lacking quantitative data. To reveal the evolutionary characteristics of the sedimentary environment, the drilled hole XDZK16-5 in Xiadian, Sanhe, was clearly measured and sampled. A total of 826 grain size samples and 7 OSL(optically stimulated luminescence) dating samples were collected. The particle size distribution of the sediment sample was determined using a Malvern Mastersizer 3000 laser diffraction particle size analyzer. The average grain size, standard deviation, skewness, and kurtosis of each sample were calculated, and frequency distribution curves and probability cumulative curves were drawn. The results show that the strata of XDZK16-5 deposited during Late Pleistocene and the strata mainly consists of fine sand, silt and clay. The frequency distribution curves are mainly unimodal and negatively skewed, with a relatively wide kurtosis. The standard deviation indicates good sorting. The probability cumulative curves are mainly two-segment types, with different cut-off points between the rolling component and suspended component. The borehole is divided into seven stages according to the lithological characteristics, the grain size parameters, the frequency curves and the probability cumulative curves. Comprehensive analysis indicates that the study area has been in a relatively weak hydrodynamic sedimentary environment with small-scale strong and weak fluctuations. In addition, a series of positive rhythms of “medium sand-fine sand-silt sand” and “silt sand-clay” appear in the strata, showing obvious characteristics of the dual structure of fluvial alluvium. This study provides basic research data for the Late Pleistocene sedimentology research in the eastern Beijing plain, and has important reference value for understanding the future climate evolution model under the influence of human activities.