OBJECTIVE: To discuss the phenomenon and the possible causes for the skeletal age less than the "real age" in the judicial expertise. METHODS: With referring to the skeletal age verification value provided by the inspection sample pertaining to CHN scoring method, combining with the relevant materials such as "age" and "residence" information provided by the police authority while performing expertise, as well as tracking down and re-visiting some cases, we retrospectively analyzed 829 cases. RESULTS: There were 303 cases for the skeletal age less than "real age" in total, which accounted for 36.6% (303/829), and accounted for 40.8% (303/742) in 742 cases with "age" cases. If the normal age range between both was less than 0.5 year (including 0.5), the numbers of such cases decreased to 190 cases, which accounted for 22.9% (190/829) and 25.6% (190/742), respectively. When the difference was within 0.5, the "age" close to the skeletal age would be more reliable. It was difficult to confirm which one was wrong if the difference was 0.6-2.0 years. However, the error possibility in "age" would increase with increasing the difference value. CONCLUSION: Many uncertain factors may lead to that the skeletal age was less than the "age". The occurring rate for the skeletal age less than "age" is not low. The identification conclusion shall be made with caution after comprehensive assessment.