The invention discloses an osteoarthritis diagnosing product; the product can diagnose osteoarthritis through detecting the expression level of a CRNN gene in a biological sample, or a CRNN gene expression protein and fragments, analogs and derivatives thereof. The invention further discloses an application of the product in diagnosis of osteoarthritis. The invention discloses the gene CRNN related with osteoarthritis, and down-regulated expression of the CRNN gene or the gene expression protein and fragments, analogs and derivatives thereof in osteoarthritis tissues is further confirmed. With use of the gene for detection of osteoarthritis, early detection can be rapidly and effectively done, and a therapeutic target and an important basis are provided for gene therapy, drug therapy and other clinical applications.