In order to understand the population dynamics of Antarctic krill(Euphausia superba Dana)in the South Shetland Islands,the main Chinese fishing ground of Antarctic krill fishery,using the biological data collected by the fishery observers,the present study analyzes the spatial-temporal characteristics of population composition of Antarctic krill based on dividing the study area into small scale units with the latitude-longitude spatial resolution of 10′ and 10′.The results show that,in the 23 units analyzed,the proportion of immature females is highest(42.1%),followed by mature females(35.6%),the proportion of males is below 20% and all individuals are immature,the proportion of juvenile individuals is only 2.7%.Compared with other periods,the individuals in juvenile stage is higher(9.6%)in the middle of December 2010 and the proportion of immature males(M₂)is higher than that of mature females(F₃).The similarity of maturity stage composition can be found in the last ten-day period of December 2010 and the first ten-day of January 2011,the juveniles can not be found in the samples and the proportion of M₂ is decreasing and the proportion of F₃ is significantly increasing.The distribution patterns of M₂,F₂ and F₃ are similar in the different water layers(PSI=90.9-97.7).The juveniles are mainly distributed in the 60 to 80 m layer(66.9%)and the individuals of F₂,M₂ and F₃ are located in the 40 to 60 m layer.