For railway operations worldwide, train rear-end collision accidents occasionally occur, resulting in heavy casualties and property loss. To avoid the occurrence of such incidents, a novel early warning method of train tracking interval based on centralized traffic control (CTC), or simply CTC interval prewarning, is proposed. When combined with the existing automatic train protection (ATP), the monitoring of train tracking interval is doubled. The proposed method calculates the minimum safety interval in real time and compares it with the actual spatial distance. When the actual spatial distance is less than the minimum safety interval, particularly when the ATP is at fault, the proposed method is capable of raising the alert and taking control measures to effectively avoid rear-end collision accidents. At the same time, this method displaces the manual supervision of train operation, thereby relieving labor intensity, and improves the effectiveness of supervision. This paper analyzes the necessity and feasibility of the proposed CTC interval prewarning method and explains the basic architecture of the system, data acquisition, tracking interval calculation, prewarning rules, and implementation. The CTC tracking interval calculation model has been established, and the table of warning distance of the different train speeds has been calculated. The reliability model of the train control system (TCS) has been established based on the CTC interval prewarning method, which is used to analyze the reliability and safety of the TCS.