Abstract: In order to study the hydrodynamic characteristics of pressure pipeline in small hydropower stations in southwest China,taking the Xiaodongfeng Hydropower Station in Dafang county of Guizhou Province as an example,a numerical simulation for 3D turbulence was carried out by using fluid calculation software CFD.The results showed that the hydraulic loss of the pressure pipeline under the average flow of the hydropower station was 0.056m,relative small.The flow velocity uniformity at the outlet of the pressure pipeline under different flow rates was above 92%,and the variation range was within 1%.At different flow rates,there was a high-speed zone at the inside of the elbow of the pressure pipeline near the runner,and there was a low-speed zone at the outside of the elbow.As the flow increased,the range of the high-speed zone inside the elbow gradually increased.When the flow rate was 8～10m3/s,the speed gradient range of the elbow was small,the vortex was little,the pressure pipeline was relatively stable,and the pressure pipeline vibration was not easy to occur.When the flow rate was too high or too low,the sudden change of partial static pressure were all large,which was not conducive to the stable operation of the pressure pipeline.The position of the largest pressure fluctuation was the inner wall surface of the pressure pipeline close to the runner.The research results can provide guidance for the study of vibration characteristics,regular maintenance and sensor installation of pressure pipes in hydropower stations.