Abstract: The cut off value or reference interval is significant in clinical testing and diagnosis. If there is no scientific and reasonable cut off value or reference interval for in vitro diagnostic reagents, clinicians can not make medical decisions on patients through the results. The test will be meaningless, so the cut off value or reference interval study is an important part of the preclinical study of in vitro diagnostic reagents. In this article, combined to the review experience of related product, we discuss the establishment and verification of the cut off value and reference interval to provide a reference for relevant manufacturers.