Abstract: Residual stress will inevitably be introduced during the manufacture of mechanical components and products. Residual stress has an important impact on component performance and service life. There are many methods for testing residual stress. As a non-destructive testing method, X-ray testing technology has been widely used in engineering due to its mature theory and simple method. The qualitative analysis and judgment of possible important influencing factors on the residual stress test results was discussed and the characterization of the error and uncertainty in the residual stress test process was briefly analyzed. The case study to calculate the uncertainty in a single laboratory by using the simplified “two-step method” was given. Finally suggestions on the application of residual stress measurement in failure analysis are also given.