he fishery production has been decreased with over-exploitation of marine fisheries resources. Cephalopoda is an important part of marine resources. The resources status of cephalopoda has been under consideration. is the major species among cephalopoda animals. Little information on resources status and variation trends of was reported. Based on the fishery resource survey in the north of South China Sea during 20002002, the present paper analyzed density index for the circadian, seasonal, and regional variation and the biological characteristics of Loligo eduli from the east of Hainan Island was significantly higher than that of from Beibu Gulf and south of Hainan Island. Density index and individual density index of in the north of South China Sea during the night were higher than those of during the day time. The highest density index (6.453 kg/h) of was observed in the east of Hainan Island. The highest individual density index (134.6 ind/h) was observed in the south of Hainan Island. The findings of seasonal variation of indicated that the density index and individual density index in summer were higher than those of other seasons. The highest index was observed during the summer in the east of Hainan Island. The density index (15.500 kg/h) and individual density index (910.0 ind/h) of in the depth of ranging from 18 m to 20 m in Beibu Gulf and the south of Hainan Island were higher than those of ranging from 100 m to 110 m in the east of Hainan Island. The catches of was the predominant in yield among the catch species, which was higher than that of among the Cephalopoda species from the northern South China Sea. In order to prevent from overfishing of fishery resources, strategies of protection and utilization for should be carried out, which make the sustainable development of fishery resourses.