Abstract: For the ventilating system of the target flight vehicle, a piping air circulation scheme is adopted. Taking the human-active area as an example, the air parameters and the volume are optimized. The results show that the air volume depends heavily on its temperature. When the temperature difference between output air and indoor air increases from 1℃, the air volume decreases significantly. However, when the temperature difference reaches 4～5℃, the decreasing trend becomes no longer so evident. There is a slight correlation between air volume and indoor air parameters. The paper also discusses the design of the final air flow and piping organization, a double-sided air outlet is proposed to be put on the corners above, while the corresponding double-sided air inlet is put at the nether corners.