The invention relates to an air purifying device and a purifying method thereof. The invention is to solve the technical problem of durable, highly-efficient and high-throughput removal of PM2.5 fine floating dust particles and partial bacteria and viruses, belonging to the technical field of air purification. The air purifying device is characterized by comprising an air injection unit, a washing bath pool and a bubble crushing system immersed in the washing bath pool, wherein air injected by the air injection unit enters the working area of the bubble crushing system from the bottom part of the washing bath pool; bubbles continuously undergo the process of generation, growth, extrusion and crushing, regeneration, re-growth, and re-extrusion and re-crushing; and through repeated contacting of air and water interfaces, the purpose of repeated washing and purifying of the air is achieved. The air purifying device provided by the invention can clean various fine particles in the air by washing, dissolves or captures harmful and toxic gases, and has good purifying effect. The device provided by the invention has the advantages of convenient use, wide application range, and applicability to indoor home application and public spaces like industrial and mining enterprises, hospitals, and station and airport halls.