使用隧道磁电阻(TMR)传感器对带包覆层的铁磁性管道的腐蚀进行脉冲涡流检测时，地磁场会对检测结果有影响。管道东西向放置时，针对70 mm包覆层铁磁性管道腐蚀，TMR磁传感器分别放置于管道正上方、相对偏转45°、相对偏转90°进行了检测试验。试验结果表明，TMR放置角度对检测有一定影响；在实际检测中，TMR的接收方向与地磁场方向的角度发生较大改变时，应重新选取检测的参考基准。

In this paper, TMR magnetic field sensor was used to detect corrosion under insulation in ferromagnetic pipes with pulsed eddy current testing. To improve detection accuracy, effect of geomagnetic field on testing was studied. A pipe with 70mm insulation was placed to the east-west and experiments were performed with TMR magnetic field sensor placed at different positions, over the pipe, the side of 45 degree from the top and the side of 90 degrees from the top respectively. The experimental results show that probe orientation has a significant influence on the detection . In actual testing, if receiving direction of TMR with respect to the geomagnetic field is changed greatly, reference standard should be reselected.