Abstract: Aiming at the problems of nondestructive testing of pipelines based on longitudinal guided wave magnetostrictive sensor,in this article,the testing principle and structure of the longitudinal guided wave magnetostrictive sensor was introduced.Based on it,the problem of the impedance matching between the receiving transducer and the receiving source was discussed deeply.The conditions of implementation and methods of impedance matching are elaborated.Optimal matching condition and the optimal capacitor of the matching circuit is obtained from theoretical calculations.Finally,experiment was designed to verify the existence of the problems of impedance matching,and the relationships among the impedance matching angle,the matching capacitance and the guided wave signal amplitude was discussed,and the best capacitance value of matching circuit under real conditions was obtained by experimental method.