The present investigation aims at exploring the urban wind environment due to the various dimensions of streets and building layouts. Such a study which involves field measurement and long term monitoring is expected and the consumption of cost is high. In order to determine the effects of several parameters which may influence the urban wind environment, CFD was employed after the validation of CFD by the comparison with field measurement results. The effects of various scales of street canyons and layouts were simulated by means of CFD and the factors studied herein include the street aspect ratio, building layout and wind speed. The average velocity ratio was used for the analysis of wind environment. Optimistically, the result obtained from this work can be useful for the architectural design and urban planning.