According to the technical requirements of thermal storage unit of solar ventilation shaft, A composite phase change materials were prepared and applied to the ventilation shaft, and a solar ventilation shaft experimental system using composite phase change material was established, and its operation performance was tested. The results showed that the thermal conductivity and the latent heat of the composite phase change material prepared by adding 5wt% carbon nanotubes were 0.65 W/m.K and 107 J/g respectively, and 2.03 times and 0.718 times of that before adding. And outlet air flow of the solar ventilation shaft experimental system using above material were 55~103.9 m³/h beteewn 10:00 to 21:00, and the time was in 17:00 to the both of maximum value. This provides a guarantee for the natural ventilation.