Abstract:In order to understand how urban development changes the variation of wind speed s,using the data of upper air and surface wind speed observed from Xingtai, Zhan gjiakou and Lao ting, Hebei Province, from 1971-2006, the characteristics o f variation of wind speeds at altitudes of 10m (surface), 300m, 600m and 900m are analyzed. The similarities and differences of wind speed changes between the dif ferent altitudes of boundary layer are compared. Results indicate that annual an d seasonal mean wind speeds of the three stations all increase with height; The maximum wind speed vertical increasing rate appears between 10m and 300m; Monthl y mean wind speeds at different altitudes for each station have the obvious char a cteristics of seasonal variation, with the largest wind speed occurring in sprin gtime, and the smallest one in summertime; Surface annual and seasonal mean wind speeds for the 3 station average undergo a significant decreasing trend during the past 36 years; Wind speeds at altitudes from 300m to 900m also see a decrea sing trend generally, but the trend is mostly insignificant statistically. Combi ned with the metadata of observational settings, it seems that the obvious diffe rence of wind speed change between the different altitudes is attributable to th e fast urbanization and the change of observational environment, which cause the slowdown of surface wind speed at the three stations. However, the change in at mospheric circulation might also contribute to the significant decrease of surfa ce wind speed, because the wind speed at altitudes of 300m to 900m experiences t he weakening trends during the same time period, in spite of the fact that the u pper layer trends are generally insignificant.