Based on the measured river topographic data of the mainstream of the Beijiang River in 2011 and 2020，the evolution law of the Beijiang River main stream in recent ten years is quantitatively analyzed from the aspects of riverbed elevation，thalweg elevation，water surface width，river facies coefficients and changes in riverbed volume. The results show that：1）The reach from Shaoguan to Mengli water conservancy project is silted，and the reach from Mengli water conservancy project to Sixianjiao is scoured. 2）The average fluvial facies coefficients of the two reaches from Shaoguan to Mengli water conservancy project are increasing，while the average fluvial facies coefficients of the four reaches from Mengli water conservancy project to Sixianjiao are decreasing. 3）The main factors affecting the evolution of the Beijiang River main stream include sand mining，reservoir construction，soil erosion，waterway improvement projects and national and local policies，among which sand mining is an important factor.