The invention discloses a control device of an air purifier. The control device of the air purifier comprises a central processing unit with a single chip microcomputer, an air sampling unit connected with the central processing unit, and a display unit receiving signals from the central processing unit and displaying the signals in real time. The air sampling unit comprises a two-position three-way reversing valve. The two-position three-way reversing valve is provided with a first sampling channel, a second sampling channel and a third sampling channel, wherein the first sampling channel and the second sampling channel are controlled to switch by the central processing unit, and the third sampling channel is communicated with an outlet of an air duct of the air purifier. The first sampling channel is communicated with indoor air not purified. The second sampling channel is communicated with purified air. An air quality sensor is disposed in the third sampling channel and is connected with the central processing unit. The central processing unit logically judges and calculates received air quality detection information so as to determine failure of a filter of the air purifier and give an alarm in case of failure.