A device for detecting blockage of an air filter mesh, including: an air inlet, an air outlet, an air duct, a fan or a wind wheel, a blower motor, an air filter mesh, and a controller. The controller includes a main control board including: a microprocessor, an inverter circuit, and a motor operation parameter detecting circuit. The air filter mesh is disposed in the air duct. The motor operation parameter detecting circuit inputs a real time operation parameter into the microprocessor, and the output terminal of the microprocessor controls the inverter circuit. A function module of the microprocessor calculates a detected air volume according to the real time operation parameter. When the detected air volume is smaller than a preset air volume, the microprocessor determines that the air filter mesh is obstructed and outputs a signal to an alarm circuit to trigger an alarm.