Abstract: Preventive test is an important means for judging whether safety tools and devices are in health, while the standardized operation for an inspection and testing organization is the premise to guarantee the preventive tests effective. By expounding the meaning of instructing the system and the classification of qualification, the relationship of system and classification is clarified, and the questions are answered whether a qualification is needed in performing preventive tests for safety tools and devices and what kind of qualification should be granted to the preventive tests.