The fence height and incoming wind velocity are the main factors affecting the spatial dispersion of construction dust. Taking a construction site in Beijing as an example, the construction dust data of a certain period was selected for CFD simulation, and the results were compared with the actual measured dust concentration data of the site for verification. By analyzing the meteorological wind velocity data during the construction period of the site, 6 kinds of incoming wind velocities of 2，3，4，5，7 m/s and 9 m/s with exponential law were selected, and 6 kinds of fence heights of 1.8, 2.0, 2.2, 2.5, 2.8 m and 3.0 m were chosen. The CFD simulations were conducted to compare and analyze the spatial distribution and dispersion characteristics of construction dust under different fence heights and incoming wind velocities. In order to comprehensively evaluate the impact of construction dust on the human body and external environment, the averaged dust emission rate in the range of breathing height 0.5~1.5 m and the dust fugitive ratio were proposed as evaluation indexes. The results show that the averaged dust emission rate of 3.0 m fence height has the lowest overall index at the six incoming wind velocities, indicating that dust pollution has the least harm to the human body. The dust fugitive ratios of the six fence heights under the same incoming wind velocity are almost the same, which indicates that the impacts on the external environment are almost the same. The impacts of the construction dust on the human body and the external environment are the most serious when the incoming wind velocity is 3 m/s and 5 m/s, respectively.