The invention provides a resonant gas sensor and a manufacturing method thereof. The resonant gas sensor comprises a detection
light source used for generating detection light capable of being absorbed by gas to be detected; the detection cavity is arranged on a light path of the detection light; the
cavity wall, opposite to one side of the detection
light source, of the detection cavity is made of a material which is transparent relative to detection light, the detection cavity is communicated with a detection environment through a through hole so as to obtain to-be-detected target gas in the detection environment, and a piezoelectric
resonator capable of changing the
resonance state along with the change of environment
sound pressure is arranged in the detection cavity. According to the invention, two substrates are adopted to respectively manufacture different structures and are assembled through bonding. And the processes of the key structures are independent from each other and cannot influence each other when different structures are manufactured, so that the process stability is high. The sensor structure adopts a photoacoustic
signal mode, the detection sensitivity is high, the response speed is high, and the detection range is large. And the detection cavity does not contain any material for absorbing the detected gas, so that timely response can be performed when the concentration is changed, and the situation of
signal lag caused by gas residue is avoided.