Using the length data of Antarctic krill collected by the fishery observers on board the large scale otter midwater trawlers, the present study analyzes the spatial temporal characteristics of length distribution of Antarctic krill based on dividing the study area into small scale units with resolution of 10′ and 10′. The results show that, the range of average length is 46.9 to 55.0 mm in the 24 units, the minimum and maximum length is 26.8 mm and 62.2 mm, respectively. Significant difference can be found among the units for the length distribution. Remarkable differences of the length distribution also exist for all units on the same latitudinal level and most units (71.4%) on the same longitudinal level. Over half of samples (60.3%) are distributed in the layer under the surface 40 to 80 m. Significant difference can be found for the length distribution among the 6 layers (0 to 120 m with 20 m interval), however, the average length is closer among the layers (52.5 to 53.6 mm). The range of length distribution and average length are 26.8 to 62.4 mm and 53.1 mm in December and 39.1 to 62.0 mm and 52.4 mm in January. Small individuals exist significantly in the middle of December, and the dominant length ranged from 32 to 35 mm, accounting for about 10%.