Abstract: Annuli character are studied in this paper by observing the scales specimens collected from 7 fish categories belong to Percoidei, which are captured in the coral reef of Nansha Islands from May to July 2004 using trammel net. We use the microscope and projection lens to observe the annuli for distinguish the groups of circuli. The results are as follows: The annuli character is mainly marked by the cut groups of circuli in the profile areas. Seen from the struture of age composition, the fish of Percoidei which were caught in the coral reef of Nansha Islands is mainly age 3 to 6 years old, was mainly related with the selectivity of gill net.At the same time, this article has discussed the attention in the experimentation and provides reference for annilu identification of fish captured from South China Sea.