The invention discloses a multi-parameter high-selectivity capacitive micromachined ultrasonic transducers (CMUTs) gas sensor and methods for using and preparing the same. SnO2, ZnO, Fe2O3, WO3 and other semiconductor metal oxides are used as top electrodes and sensitive identification materials of CMUTs; and on the basis of the characteristics of causing the film mass and top electrode resistancechanges simultaneously after gas absorption, high-selectivity sensitivity of gas molecules with similar physical or chemical properties is realized. The resonant frequency change of the CMUT is caused by the film mass change and the change of the AC voltage amplitude between the top electrode and the bottom electrode of the CMUT is caused by the resistance change of the top electrode, so that change of the vibration amplitude of the CMUT film is caused. The high-selectivity detection of the gas molecules is realized by changes of two output parameters of the resonance frequency and the film vibration displacement amplitude. Besides, since the semiconductor oxide sensitive material can be used repeatedly under the temperature regulation, the CMUT gas sensor has high selectivity and high repeatability.