Abstract: Addressing the problem that during the operation process of the magnetic flux leakage steel tube flaw inspection system, on-line judgement of the probe status thereof is impossible, a specialized device for quick on-line probe status judgement is designed.Elaborated in details in the paper are configuration, principle and actual operation circumstances of the said device.Thanks to the device, on-line monitoring of the probe state is realized, and the probe performance can be quickly determined.As a result, inspection/maintenance time of the probe shall be tremendously reduced, and thus the efficiency of the detection system enhanced, and the probe position accurately located.The practicability and reliability of the device are validated via massive preliminary testing activities, and actual operation effectiveness.