The invention discloses a portable device for quantitatively cutting and installing tunnel TSP emulsified explosive and an application method thereof. The portable device comprises a box, whose top plate can be opened through rotation. A cutting blade is fixedly arranged on the bottom of the top plate. An integral explosive loading groove is detachably arranged in the box. The middle of the integral explosive loading groove is provided with a cutting groove that is matched with the cutting blade. A quantitatively adjusting device is arranged in the integral explosive loading groove, thus the emulsified explosive can be quantitatively cut through the cooperation between the cutting blade and the cutting groove; the cutting groove of the integral explosive loading groove is provided with a rotation shaft, and through rotating the integral explosive loading groove around the rotation shaft, the integral explosive loading groove can be converted into a portable explosive box. The provided device is suitable for the operation in a tunnel, the efficiency is improved, the comprehensive performance is strong, and the work for the operator becomes easier.