Abstract: Analyzed here in the article are diameter change，and changes of relevant properties of the Φ1 219 mm×18.4 mm X80M SAWH tube after being subjected to hydrostatic test，including tensile properties，guided bending，and residual stress，etc..The result shows that compared with correspondent before-test-data，properties of the tube after being hydrostatically tested like yield strength，yield ratio and percentage elongation at maximum force，etc are obviously changed，i.e.，yield strength is increased by 10.9%，and yield ratio by 10%，and percentage elongation at maximum force is decreased by 10.8%，whereas the tensile strength changes a little，just going up by 1.1%.Accordingly it is proposed that tube sampling be conducted after the hydrostatic test to analyze welding performance of the finished X80M tube.