The invention provides a compound air cleaning agent and a preparing method and application thereof. The compound air cleaning agent is formed by compounding multiple components of thyme essential oil, tea tree essential oil, castanea mollissima flower extracting solution, peony root and skin extracting solution, vine tea extracting solution, gardenia essential oil, osmanthus fragrans essential oil, costustoot essential oil, may lily of the valley alcohol, nerol, citric acid, 2-isopentyloxy allyl acetate, alcohol, assistant, 4-hydroxy-3-butylphthalide and deionized water. The air cleaning agent has the advantages of better sterilizing, mosquito repelling and aroma enhancing performances due to proper selecting of component and proportion and the coordinated action among the components, less using amount, long time effectiveness, and is more saved and fast in the aspect of life and use of people.