This standard specifies the method of constant humidity cabinet test for sintered NdFeB permanent magnets. According to the different steam pressures in the test chamber, the constant humidity cabinet test is divided into ordinary constant humidity cabinet test, high voltage steam constant humidity cabinet test (including HAST test and PCT test). It is suitable for sintered NdFeB permanent magnets with covering layers, such as metal protective layer, coating and conversion film layer, and constant humidity cabinet test for irreversible loss of magnetic flux before measurement in open circuit state. The standard cites relevant test methods and terminology to ensure the Reliability and standardization of test results.