Gas concentration detection device

A gas concentration detection device comprises a shell and a circuit board assembly. The shell is provided with a vent hole penetrating through the shell, the gas concentration detection device is provided with an inner cavity, and the vent hole is in gas communication with the inner cavity. The circuit board assembly is at least partially located in the inner cavity and comprises a circuit board and a gas concentration detection sensor connected to the circuit board. The shell comprises a first shell body and a second shell body, the first shell body comprises a bottom wall and a first peripheral wall extending upwards from the bottom wall, the second shell body comprises a top wall and a second peripheral wall extending downwards from the top wall, and the first peripheral wall is matched with the second peripheral wall. The gas concentration detection device further comprises a sealing ring clamped between the first peripheral wall and the second peripheral wall, and the waterproof performance of the gas c