Aiming to the problem of the inspection of small diameter bending pipes using torsional guided wave, finite element method and experiments were used to investigate the problem. ANSYS was used to simulate the propagation of torsional guided wave in bending pipe. A magnetostrictive torsional guided wave transducer was designed to inspect small diameter pipes. The exciting and receiving theoretical model of the transducer was built. The experimental signals were explained by using the theoretical model. Research results show that mode conversion happens at the elbow of the pipe and part of the T(0,1) mode converts to F(1,1) mode. The orientation of the F(1,1) mode perpendicular to the direction of extrados-intrados. The double end reflection phenomenon in inspection signal is caused by mode conversion. With the increase of frequency, the ratios between end echoes′ trend towards alleviation. The longitudinal magnetostrictive forces excited by the transducer bring about small longitudinal guided wave in the signals. Conclusions will provide theoretical guide to the inspection of small diameter bend pipes using magnetostrictive torsional guided wave.