The invention provides a kit for rapidly evaluating compost maturity and an application method of the kit, which are applied to the field of environmental chemistry and microorganism. The kit comprises a detection tank, CO2 gel test paper, NH3 gel test paper and a result indication card, wherein the kit employs the CO2 gel test paper to detect CO2 absorption rate of compost, and the NH3 gel test paper is used for detecting NH3 volatilization rate of the compost, comparing with the result indication card according to a detection result of the CO3 gel test paper and the NH3 gel test paper and determining the compost maturity. The kit detection method is simple, convenient and rapid, is high in sensitivity and does not dependent on high-cost instrument and equipment, a person without experiment experience can rapidly master experiment skills within short time, and sample detection is completed within 30 minutes. The kit can be used for conventional detection of the organic solid waste compost process such as livestock excrement, municipal sludge and kitchen garbage, and simple, rapid and sensitive detection method and evaluation basis is provided for compost maturity evaluation.