Wind-driven rain is defined as the quantity of rain that passes through a plane with defined orientation in the atmosphere. It is well known that rain water (wind-driven rain) causes more than 90 percent critical damage to buildings. As the most important boundary condition, wind-driven rain has significant effect on the accuracy of hygrothermal building component simulation. The existing wind-driven rain estimation approaches have limits. They are either: 1) over simplified and cannot capture comprehensive essential effects, or 2) too complicate to perform. 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. Based on observations and statistical analysis, the correlation between wind pressure and wind-driven rain was studied. As a result, a new parameter, wind pressure Pdr, is used in this new model which is in conjunction with M. Grosso's wind pressure model. As a parametric model, the WDR-Pdr model is convenient to use and it economizes the complicate processes of CFD simulation and data processing.