The natural ventilation in a novel built-in photovoltaic-Trombe wall (BiPV-TW) was numerically simulated by CFD method. The effect of solar radiation, channel width and height on the air flow pattern and ventilation rate was analyzed. Results show that the solar radiation, channel width and height influenced the ventilation rate remarkably. As the solar radiation and BiPV-TW height increased,the ventilation rate increased. As the channel width increasing from 0.1 m to 0.4 m, the ventilation rate monotonously increased. However, when the channel width exceeded 0.5 m, the reverse flow was formed in the top zone and the ventilation rate decreased. A maximum air volume flow rate was achieved when the channel width was approximately equal to 0.4 m in a 3 m height model. The channel width was the dominant factor that influenced the flow pattern in the channel. When the channel width was smaller than 0.4 m, the airflow was thermally stratified laminar flow. When the channel width exceeded 0.5 m, thermally stratified flow disappeared due to the reverse flow formed in the top zone and the laminar flow became turbulent.