Air purifying system and air purifying method

The invention discloses an air purifying system. The air purifying system comprises a casing, wherein an air inlet port for inputting outdoor air, an air return port for back sucking indoor air and anair outlet port for outputting air to the inside are formed in the casing; a physical air purification unit, a biochemical air purification unit and a fan are sequentially arranged in the casing fromfront to back; an input port of the fan is located on the back side of the biochemical air purification unit, and an output port of the fan is communicated with the air outlet port; the air inlet port and the air return port are both located on the front side of the physical air purification unit. The invention also discloses an air purifying method. Particulate matter pollutants can be removed in a physical dust removal manner, bacteria and microorganisms attached to particulate matter can be killed, pollutants such as formaldehyde can be removed in a physical dust removal manner, and growthof microorganisms such as