In practical engineering, inclined building walls are often presented due to their functional and aesthetic needs. A reasonable air distribution design is essential for creating a satisfactory indoor environment in such buildings. In the present study, inclined wals with a variable inclination angle β were used as the research object to explore a novel air supply mode. Visualization experiments and numerical simulations were conducted to investigate the induced airflow, such as the airflow pattern, the airflow characteristics (maximum jet velocity decay and jet spreading rate) and the ventilation effect (vertical air temperature difference, draft rate, air diffusion performance index). The results show that the “air lake” phenomena occurred over the floor, which resembles the displacement ventilation to some extent. The proposed air supply mode has a good ventilation effect and could be applied to building spaces with inclined walls. The current study can be used as a reference for ventilation design in buildings with inclined walls.