To accurately obtain the influence of slope transition sections on the wind field characteristics of the terrain model， this study used the large eddy simulation （LES） method to conduct numerical simulation of wind field characteristics in the transition section of slopes with different slope ratios. At the entrance of the computational domain， numerical turbulent flow was generated by the narrow band synthesis random flow generation （NSRFG） method . The slope ratio ξ（=L/h） of the slope transition section was defined （ξ takes the values of 0， 1， 2 and 3， where h is the slope height and L is the slope length）. The results show that when the incoming flow reaches the slope transition section， a backflow is formed at the bottom of the transition section， the wind speed is significantly reduced， and the turbulence intensity is also reduced. When the incoming flow reaches the top of the slope transition section， the wind speed increases significantly， and the turbulence intensity also increases. When the incoming flow passes through the slope transition section， the mean wind speed profile gradually returns to the same as that of the inlet. In addition， the larger ξ can result in better transition effect， lower vortex shedding frequency， more uniform vortex shedding frequency at different heights， smaller variation in wind speed amplification factor， and larger turbulence integral scale. The transition effect is best when ξ=3， and it returns to the same as the inlet wind speed profile at x/h=2， and the wind speed amplification factor returns to 1 at the more advanced position. This study can provide a reference for the design of boundary transition sections of terrain models for wind field characteristic measurement.