Abstract: Furnace tube as an important component of large tube type fuel heating furnace used in petroleum chemical industry not only is of the high cost of investment accounting, but also is of the highest frequency component failure. Therefore, the adoption of effective detection techniques to test tube oxidation degree is very important. This paper uses acoustic emission detection technology and magnetic detection technology to test magnetic signal and acoustic signal of the fire surface, back surface and transition surface about the tube of φ114 mm×6.5 mm (outer diameter×wall thickness) and has been on active service for 50000 hours. Through comparison of different results of testing under various oxidation degrees, the detection effectiveness of magnetic detection technology and acoustic emission detection technology was investigated. Results show that, the magnetic detection technology and acoustic emission detection technology can be used in furnace tube oxidation degree detection. The coercive force depends on the size of the furnace tube degree of oxidation and the degree of adhesion of oxidation layer, and acoustic signal attenuation gradient is more sensitive to the change of the oxide layer thickness, and the thicker the thickness of the oxide layer, the greater the acoustic attenuation gradient is.