The air-conditioned room in small space is studied by establishing the mathematical model of the air flow arrangement for energy saving. The energy saving effect is analyzed numerically at different angles under circumstance of the most common way of one-side up supply and down return. Our results show that if air supply angle is set at , the energy utilization coefficient is maximum value,and air condition reaches best energy-saving state. Our design method can be referenced valuably for the air exit design and regulating of air-conditioned room in real project.