The invention discloses a cleaning reminding method for an air conditioner filtering device. The method comprises the following steps that S1, the air inlet temperature and the air outlet temperature of an indoor unit are collected, and in addition, a different value between the air inlet temperature and the air outlet temperature is calculated; S2, when the different value between the air inlet temperature and the air outlet temperature is greater than a temperature difference preset value, the opening degree of an electronic expansion valve is detected; S3, when the opening degree of the electronic expansion valve is greater than a first opening degree preset value during heating or the opening degree of the electronic expansion valve is smaller than the second opening degree preset value during refrigeration, warning is carried out. The cleaning reminding method for the air conditioner filtering device disclosed by the invention has the advantages that the cleaning can be carried out according to the actual work condition of the filtering device, further, the labor and material waste caused by regular cleaning can be relieved, meanwhile, the filtering device can be cleaned in time, and the heat exchange efficiency of an air conditioner can be ensured. The invention also discloses a cleaning reminding device for the air conditioner filtering device adopting the cleaning reminding method.