Abstract: Based on the indoor generalized model, this paper considered the wide-and-narrow reach of Baoxing River as the research object; measured the three-dimensional instantaneous velocity based on the typical section of the indoor model using the acoustic Doppler velocimeter; and analyzed the distribution of longitudinal velocity, turbulent intensity, Reynolds shear stress, and turbulent kinetic energy based on the typical section to explore the flow turbulence characteristics of the river. The experimental results revealed that in the wide-and-narrow flume, the turbulence intensity on the side walls of the diffusion section was higher than that in the central region, and the maximum value was observed at 0.2 times the water depth; the maximum turbulent kinetic energy was generated at the foot of the slope on both sides of the diffusion section; the maximum values of the plane Reynolds shear stress and the vertical Reynolds shear stress on both sides of the wall appeared in the diffusion section, while the maximum Reynolds shear stress value of the central area was observed at the middle segment between the two grooves; and the vortexes generated on both sides of the diffusion section strengthened the lateral wall erosion and widened the channel. This study analyzed the turbulent characteristics of wide-and-narrow channels, and the analysis was beneficial for the mountainous river management and the prevention of natural disasters.