The invention relates to a mildew-removing and deodorizing dry cleaning agent for a carpet and a preparation method of the dry cleaning agent. The dry cleaning agent comprises the components in parts by mass as follows: 30-45 parts of cellulose acetate, 5-12 parts of dioctyl sodium sulfosuccinate, 2-4.5 parts of cocamidopropyl betaine, 35-55 parts of water, 1.2-3 parts of sodium metabisulfite, 4.5-8 parts of 1,2-propylene glycol 1-monomethyl ether, 0.5-2 parts of essence and 75-90 parts of 1-bromopropane. According to the dry cleaning agent and the preparation method of the dry cleaning agent, the dry cleaning agent is convenient to clean, can effectively remove stains, such as coffee, drinks, shoe polish, printing ink and the like on the carpet and has good mildew-removing and deodorizing effects, so that the carpet is kept clean and sanitary.