The vapor transportation properties and surface anti-pollution abilities of AAO/PTFE composite membrane encapsulated humidity sensor were researched. PTFE thin films with porous structures were prepared on the bi-pass AAO template using spin coating method, and used on the package windows of the humidity sensor. The static error and dynamic response were studied to evaluate the influence and protective effect of the AAO/PTFE composite membrane on the sensors in environments with constant temperature and varying humidity and in paint room, which were then compared to those of PTFE and PVDFA films. According to static and dynamic response results from humidity sensor testing, the maximum relative error reached 15% in the AAO/PTFE composite membrane encapsulated humidity sensor and three regimes could be identified: low humidity regime (30%~50%), medium humidity regime (50%~80%), and high humidity regime (>80%). Different air flow rates in different humidity regimes resulted in the differences of static measurements while the differences of dynamic measurements were resulted from the humidity difference between the inner and exterior of the tube in different humidity regimes. PTFE thin film not only kept the high porosity of AAO template but also improved its surface anti-pollution ability.