The invention discloses a stem-loop structured combined probe and application thereof. The probe is constituted by two DNA sequences of stem-loop structures; from 5' terminals to 3' terminals, probe I and probe II sequentially include stem-loop zones and detection object recognition zones, and are applicable to telomerase activity, RNA and DNA detection and telomerase inhibitor screening; when a detection object is telomerase, the detection object recognition zone of the probe I is a telomerase substrate sequence, and the detection object recognition zone of the probe II is a sequence which is complementary with 8-40 bases in a telomerase extension sequence; and when the detection object is RNA or DNA, the detection object recognition zone of the probe I is a sequence which is complementary with 8-40 bases, close to the 3' terminal, of to-be-detected RAN or DNA, and the detection object recognition zone of the probe II is a sequence which is equal to 8-40 bases, close to the 5' terminal, of the to-be-detected RAN or DNA. The combined probe disclosed by the invention is unnecessary to make use of fluorescence labeling and radioactive element labeling, and the combined probe, with the specific stem-loop structure, provides a specific amplification template for a nucleic acid amplification reaction, so that rapid signal amplification under constant temperature is achieved; and the combined probe is high in sensitivity and amplification efficiency.