A smog alarm disclosed by the present invention comprises a smog sensor used for detecting the smog concentration, a battery used for supplying power to the smog alarm, a wireless module used for realizing the communication between an MCU and a mobile terminal, a self-inspection and monitoring circuit used for detecting the working state of the smog sensor, an electric quantity detection circuit used for detecting the residual electric quantity of the battery, the MCU used for controlling the self-inspection and monitoring circuit to detect the working state of the smog sensor and controlling the electric quantity detection circuit to detect the residual electric quantity of the battery according to the received self-inspection instructions sent by the pre-bound mobile terminal, obtaining the detections results of the self-inspection and monitoring circuit and the electric quantity detection circuit, and sending the detection results to the pre-bound mobile terminal via the wireless module. The smog alarm provided by the present invention can be controlled to detect automatically via the mobile terminal, and sends the detection results to the mobile terminal, thereby improving the fault elimination capability of the smog alarm and the user experiences.