Abstract: Based on the bottom trawling data of two cruises in the offshore waters of Hainan Island in April and September 2017,the species composition and community characteristics of the nekton in this area were analyzed.The results showed that there were 215 species of the nekton,belonging to 23 orders,97 families and 153 genera.The mean biomass of fishery resources in spring and autumn were 751.61 kg/km² and 1 426.03 kg/km²,respectively.The average values of Shannon-Wiener species diversity index H' in spring and autumn were 3.44 and 3.63,respectively,and the average values of Margalef species richness index D in spring and autumn were 4.38 and 5.29,respectively.The average values of Pielou species evenness index(J) in spring and autumn were 0.68 and 0.69,respectively.The dominant species were Acropoma japonicum,Trachurus japonicus,Squilla oratoria and Portunus argentatus.In spring,the dominant species showed miniaturization and low quality,and in autumn,the proportion of economic species increased.The results of ABC curve and W value showed that the community of the nekton was in a serious disturbance state and the community structure was not stable.