The invention relates to a system utilizing CMMB (China mobile multimedia broadcasting) signals to detect a target and a method thereof. The system comprises a receiving antenna, an analog chassis with a signal simulating and receiving component, a CPCI (compact peripheral component interconnect) chassis with a signal acquisition and processing component, at least one disc array chassis with a signal storage component, a switchboard and a signal process for signal processing, which are connected in sequence. The analog reception adopts a scheme of secondary mixed frequency and fixed medium frequency; the data acquisition adopts a scheme of medium-frequency bandpass sampling and digital down-conversion; the data storage adopts a high-speed disc array; and the data processor is used for implementing such operations as signal reconstruction, channel correction, direct wave suppression, digital beam formation, inter-ambiguity function, peak detection, constant false alarm detection, positioning and tracking and the like, and final output of information of the target distance, speed and direction. The system has the following advantages of no need for frequency distribution, no electromagnetic pollution, high signal randomness, high signal interception performance, large signal bandwidth, high distance resolution, low research and maintenance cost, and high mobility.