Abstract: Abstract: Pollutants are easy to be concentrated in the underground space because of the low terrain and the enclosure space. Therefore, an effective ventilation system is required to create a clean indoor environment. Ventilation fan is widely used in the underground space, but the fan has high energy consumption and is very noisy. Thus, both energy conservation and environmental protection are significantly important for the design of ventilation system, and solar chimney is a feasible method by using solar energy in order to realize these 2 purposes. Due to the special underground space environment, it's impossible to construct a solar chimney as the ground building, which must be combined with other technologies. PV (photovoltaic) technology is a common solar energy utilization technology, but most of solar energy irradiating on PV cells is converted into heat when it is operating, resulting in a rising PV temperature and a dropping photoelectric conversion efficiency. In this project, photovoltaic-thermal technology is used to recover the heat of PV cells to maintain a high photoelectric conversion efficiency. This paper proposes a system combining the solar chimney effect with the photovoltaic-thermal technology for the purpose of enhancing the natural ventilation in the underground space. On one hand, this system can maintain the PV temperature at a high photoelectric conversion efficiency. On the other hand, the extra heat can be used in the underground space ventilation. Therefore, the ventilation energy consumption is reduced and the comprehensive utilization efficiency of solar energy is increased. To study the influencing factors of the ventilation system, a mathematical model for evaluating the ventilation performance of the ventilation shaft is established based on the conservation of energy and mass, which is solved by MATLAB software. The influences of heat exchanger tube row, height of ventilation shaft, water temperature and velocity on the ventilation performance are analyzed. Results show that the heat exchanger has a maximum effective tube row in each case, and the tube pitches of 0.032, 0.038 and 0.047 m correspond to the maximum effective tube rows of 9, 13, and 18, respectively. The outlet air temperature increases with the tube row, while the air mass flow rate increases and then decreases with the tube row. The air mass flow rate obviously increases with the height of ventilation shaft and the inlet water temperature, while it slowly increases with the water velocity. The outlet air temperature decreases with the height of ventilation shaft and increases with the water temperature and the water velocity. Finally, an empirical formula for calculating the air mass flow rate is fitted.