The aim of the present study is to develop a new wind-driven rain model, the WDR-Pdr model. Field measurement, CFD (Computational Fluid Dynamics) simulation and statistical analysis are used in this study. By using the WDR-Pdr model, wind driven rain on building facades in street canyons can be estimated. During the study of the wind-driven rain model, more influencing factors such as the density of buildings and the arrangements of the surrounding buildings are taken into account.