Abstract: In order to compare the detection capabilities of stray magnetic field and eddy current detection techniques for martensite content in austenitic stainless steel, a series of standard test blocks for ferrite content, a series of martensite content samples, and pipeline elbow workpieces were prepared. Two detection techniques were carried out, including signal response tests for different martensite contents, magnetic anisotropy tests, detection tests for different martensite contents of the same material, and on-site pipeline elbow detection tests. The experimental results showed that due to factors such as magnetic anisotropy of the workpiece and environmental magnetic field, the correlation between the detection results of stray magnetic field detection technology and martensite content was poor. However, these factors had a relatively small impact on eddy current testing technology. Therefore, for on-site detection of martensite content in austenitic stainless steel, eddy current testing technology was superior to stray magnetic field testing technology.