The present disclosure relates to a plant purification device and control method thereof. A plant purification device includes a plant purification unit and a physicochemical purification unit with adjustable use efficiency, wherein, the physicochemical purification unit is communicated with the plant purification unit; the plant purification device further includes a control module, a contaminant concentration sensor for detecting concentration of indoor contaminants, an air speed detector for detecting air speed of gas entering the plant purification unit, and a fan for driving gas to be supplied into the plant purification unit from the physicochemical purification unit, wherein, the control module is used to adjust the use efficiency of the physicochemical purification unit according to the concentration of indoor contaminants, adjust rotating speed of the fan according to a detection signal of the air speed detector, and further control the air speed of the gas entering the plant purification unit.
