Acoustic emission sensor

The invention discloses an acoustic emission sensor. One end of a casing is provided with a front cover, and the other end of the casing is provided with a back cover plate; the inner wall of the cavity of the casing is provided with a filling sleeve, and the inner wall of the filling sleeve is provided with a piezoelectric element sleeve; the front end of the piezoelectric element is arranged onthe front cover plate by a conductive adhesive tape which is covered on the piezoelectric element, the back end of the piezoelectric element is arranged on a circuit board of a preamplifier by a spring, a conductive adhesive tape is covered between the back end of the piezoelectric element and the spring, one end of a conductor is welded on the conductive adhesive tape on the back end of the piezoelectric element, and the other end of the conductor is welded on an input end of the preamplifier; the circuit board of the preamplifier is fixed on the back cover plate. The acoustic emission sensor is used for receiving grinding sound signals transmitted by air, directly eliminates interferences of machine noises on effective signals and has the advantages of reasonable structure, convenient usage, high sensitivity, wide response frequency band and low price.