The invention discloses a prestressed duct slurry stripping degree detecting device based on recursive singular entropy. The prestressed duct slurry stripping degree detecting device based on the recursive singular entropy comprises a signal stimulation module, a signal acquisition module, a signal processing module and a display and judgment module. The signal acquisition module comprises a transmitting transducer and a receiving transducer array. A sliding rod is arranged on the outer surface of a concrete structure, and the sliding rod and a steel stranded wire are arranged on the same horizontal plane and are parallel to each other; the transmitting transducer and the receiving transducer array are connected with the sliding rod in the mode that the transmitting transducer and the receiving transducer array can slide relative to the sliding rod. The invention further discloses a prestressed duct slurry stripping degree detecting method based on the recursive singular entropy. According to the prestressed duct slurry stripping degree detecting method based on the recursive singular entropy, a recursive array constructed through echo signals has the structural vibration characteristic, calculation is conducted based on the recursive array by means of the singular entropy algorithm, so that the recursive singular entropy is obtained, and the recursive singular entropy is used for judging the size of stripped slurry in a duct. By the adoption of the prestressed duct slurry stripping degree detecting device and method based on recursive singular entropy, quality detection and maintenance of concrete structures of bridges, buildings and the like can be effectively achieved, the reliability is high, and actual application and popularization are facilitated.