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The Xujiahui district of Shanghai is a typical nonhomogeneous urban terrain, with densely distributed architectures of different heights. In this paper, the distribution characteristics of roughness length are studied by using the geographic information of this area. Based on the measured wind data at the height of 80 m, the relationships among the mean wind velocity, turbulence intensity, gust factor and roughness length under the Typhoon Chanhom and the normal wind are analyzed. The results show that the differences of building heights and distribution densities in the calculated sectors corresponding to different wind directions led to the obvious variation of roughness length with wind direction, but the variation amplitude decreased with the increase of calculated sectors. The maximum value of mean wind velocity under Typhoon Chanhom was larger than that under normal winds, and there was little difference in the range of roughness length variation, but the median value of the roughness length under Typhoon Chanhom was small and the distribution was relatively concentrated. Under Typhoon Chanhom, the turbulence intensity in all directions decreased with the increase of mean wind velocity, but did not change with the roughness length. Under normal wind, the turbulence intensity in each direction does not change with the mean wind velocity, but increases with the increase of roughness length. Under typhoon Chanhom and normal wind, the gust factor in all directions increases with the increase of turbulence intensity, but the former values are slightly larger than the latter.