Based on the data obtained from the Tianjin 255m meteorological tower in recent 10 years, the surface roughness was estimated by using logarith mic wind profile under the condition of neutral stratification. The results show that the surface roughness is increasing with the development of the urb anization in recent decades．The increased amplitude of the surface roughness over urban land surface is not the same in different azimuth, which is acco rded with the urban construction speed． At the same time, the effect of urbaniz ation on the urban wind field structure was studied. It shows that wind directio n especially near the ground is affected most, and the wind speed, especially ne ar the ground, decreased year by year. The thickness of urban canopy increased 10 m during the last 10 years, and now is between 40～60m.