The invention relates to a device for measuring a clean air quantity attenuation rate of an air cleaner, and belongs to the technical field of indoor air cleaner performance detection and evaluation. The device comprises a pollutant generation device, a sealed cabin, a pressure release valve, a fan, a temperature, humidity, particle, and VOCs sensor, an air pump, a programmable logic controller, an air cleaning unit composed of a nafion tube, an activated carbon filter mesh, a first air valve and a second air valve, and a humidifying module composed of a humidifier, and a third air valve and a fourth air valve connected at two ends of the humidifier. According to the device, the structure is simple, the operation is convenient, the performance parameter of removing particles and VOCs by a to-be-detected air cleaner can be simply and conveniently evaluated and the service life is evaluated.