Solar Ventilation System is unstable and uncontrollable, so a new technology is proposed to get a system that takes solar energy as heat source and applies phase change material in daytime to store energy which is used to keep ventilation in nighttime by thermal pressure. This new system is helpful to get the ideal ventilation effect for buildings. Through the experiments on ventilation with PCM of 63℃ and 44℃, ventilation rate change curve is obtained to analyse ventilation system efficiency. The results indicate that using the PCM of 63℃ and 44℃, the total ventilation of the solar ventilation system in 10 hours are respectively 8066 m3 and 6154 m3 at night, and the average ventilation per hour and area are 538 m3/h and 41 m3/h. Based on the experiment, when PCM is palmitic acid, the ventilation effect is superior than that of lauric acid. To sum up, the system of conventional solar rooftop ventilation system combined with phase change materials can intensify the nature ventilation effectively in nighttime for buildings, improve indoor thermal environment and reduce the energy consumption in air conditioning building.