Gad humidity detecting device

The invention discloses a gas humidity detecting device which comprises a host, a detection gas chamber and a sealed connecting piece. The host is provided with a tunable semiconductor laser unit used for emitting light signals. The detection gas chamber is connected with the host, a plurality of reflective units used for reflecting light signals are arranged in the detection gas chamber, and the reflective units receive and reflect the light signals emitted by the tunable semiconductor laser unit. The sealed connecting piece is connected between the detection gas chamber and gas to be detected in a sealed mode and used for introducing the gas to be detected into the detection gas chamber. According to the gas humidity detecting device, the gas humidity in the electric system micro water environment can be accurately measured.