Film bulk acoustic resonator（FBAR）is a kind of piezoelectric transducer with excellent properties. A sealed air room FBAR is fabricated by sealing air in the back side of a back etched FBAR. The feasibility of the sealed air room FBAR as a temperature sensor is studied. The experimental result shows that, in the temperature range of 20 100 ℃, the parallel resonance frequency of the sealed air room FBAR temperature sensor decreases linearly with the rising of the temperature. Furthermore, the relationship between the resonance frequency and temperature is stable and reliable.