[Objective] To research the erosion morphology characteristics of river section in order to provide a scientific basis for the evolution of landform hydrological of downstream, the analysis of the impact of human activities and the rationality of the runoff(sediment) of upstream.[Methods] Based on the data of Shanshui and Makou stations in Pearl River dalta, Indices of the river section erosion morphology were derived. By using simulated annealing algorithm to optimize the projection pursuit model, we analyzed the evolution characteristics of river erosion morphology.[Results] As the actual ratio in 2009 of the Sanshui station was much higher than that in other years, the river section erosion in 2009 was completely different from other years. Changes in erosion patterns of other years were stable in Sanshui station. For Makou station, in spite of more erosion morphology changes, according to 5 indicators which reflect the erosion morphology of river section, the variation types of the section shape can be divided into 2 types of erosion morphology.[Conclusion] In summary, the sectional area in Makou and Sanshui station increased since 1990s, and the water capacity showed an increasing trend.