As a new-style building, the thermal performance of double skin facade with the venetian blind cannot be predicted for the absence of suitable tool. In the paper, a detailed analysis of the thermal process in glass double facade with venetian blind was made. The governing equations were solved by comprising CFD, optical and heat balance model for multi-layer transparent system. It is shown that the more complex natural ventilation exists in the two air gaps divided by venetian blind, which cannot be reflected with the simplified model. Comparing the simulation results with the experiment data in the literature, a good agreement was achieved. Hence, it can be used as a reliable tool to analyze the ventilation in the double skin facade with a venetian blind. (C) 2008 Elsevier B.V. All rights reserved.