Abstract: To improve the excitation and reception performance of surface wave EMAT and increase the accuracy for quantitative defect detection, the influence of wire length in meander-line-coil on the frequency characteristic, acoustic beam directivity and attenuation were studied experimentally. Meander-line-coils with different wire lengths were used to detect the artificial cracks, the reflection and transmission coefficients of surface wave were obtained, and the influence of the relation between wire length and crack length on quantitative detection of defect was analyzed. Results show that the frequency characteristic is independent of wire length, while the beam directivity and attenuation of surface waves are closely related to it. With the increase of wire length, the radiation half angle of surface waves beam decreases and the attenuation slows down. The space resolution of EMAT is reduced and the SNR of received signal increases with the increase of wire length when the EMAT is used as a receiver. The reflection and transmission coefficients can be measured accurately only when the wire length of meander-line-coils is smaller than the crack length.