Abstract: Descriptions were made of the theory of electromagnetic acoustic transducer (EMAT) technology. The optimization design, test method and effectiveness of the two important parts of electromagnetic acoustic transducer of high-frequency coil and electromagnet were expounded. The detecting effectiveness of EMAT for the sheet material and tubular products were illustrated with examples. Moreover the advantages and limitations of this method were also shown. Test results show that the method can be used to test the sheet material and tubular product and its reliability, accuracy and detection efficiency are better than the AUT. It is a new-style NDT method. It is considered that electromagnetic acoustic transducer technology will be widely used in petroleum industry.