The invention provides a kit for quickly detecting water-soluble explosives and a detecting method of the kit. The kit comprises 13 detection reagents; various cations, anions and molecular compounds in the water-soluble explosives and explosive residuals can be detected quickly and accurately by the kit; and the detection varieties include nitrate, nitrite, chlorate, ammonium, urea, permanganate, chloride ions, sulfur ions, sulfate, phosphate, sugar, sodium ions and potassium ions. The kit provided by the invention can be used for on-site explosive searching and quick determination of the nature of an explosive case, has the characteristics of simplicity, quickness, strong specificity, sensitive response, convenience in use and low cost, and can provide an effective technological means for the criminal investigation department of the public security system to solve explosive cases. The kit not only can be used for quickly detecting traditional explosives and explosive residuals, but also can be used for quickly and effectively detecting special explosives and explosive residuals in Xinjiang region.