The invention relates to a Q245R material nondestructive stress test method. By taking the measured coercivity value of the device under test into different formulas in different states, the stress value of the device under test can be obtained. The method can realize accurate and quantitative testing of stress states of Q245R materials. In the invention, according to the characteristics of the magnetization of the Q245R materials and the magnetic memory parameters, the test efficiency is high; tests can be carried out repeatedly to facilitate the re-inspection. The method of the invention can carry out the non-destructive field nondestructive testing on the equipment and pipelines produced with the Q245R materials; the detection process is simple and effective; and requirements for surface conditions of the equipment are not high, thereby saving the testing cost. The method of the invention makes clear the load states of the pipelines, equipment, etc. to prevent accidents related to stress synergy so as to reduce enterprise losses and bring obvious social benefits.