Abstract: Performance and energy conversion mechanism of a wind-driven fan installed on roof were studied through kinematical analysis and experiment. Most of the meniscus fan blades can generate a driving torque under the action of natural wind to rotate the fan and prevent the downward shearing wind from counter pressure difference which is unfavorable to natural draft, no matter what the incident angle of natural wind is. On the other hand, the fan's draft inducibility is enhanced somewhat with increasing wind speed. It implies that the fan itself has a draft inducibility to a certain extent in addition to that due to power density difference, and the investigation on how to utilize the low power density wind energy will be a new way to develop renewable energy resources.