To understand the effects of fishing and factors influencing the Antarctic krill () trawl operations, operation parameters, net depth, acoustic data, and other information were collected by the krill trawler "Long Teng" of the China National Fisheries Corp., Ltd. fishing in the Southern Ocean from December 2017 to June 2018. The mass center depth and expected catches in the net of the Antarctic krill swarm were obtained by an acoustic method, and the fishing efficiency was quantified based on the net position and fishing log. Then, the GAM statistical model was used to analyze the degree of deviation between the net position and mass center of the krill swarm under different towing speeds and warp lengths to study the fishing efficiency of the net. The results showed that:(1) The depth of the krill swarm mass center was (37.29±9.72) m, the depth of the net position during stable towing of the trawl was (30.72±10.41) m, the adjustment range of the net position was (11.52±7.09) m. The deviation between the net position and the mass center depth of the krill swarm was (6.33±3.58) m. (2) The catch per haul was (16.25±6.77) t, the total amount of krill entering the net mouth when the net mouth was always aligned with the krill swarm mass center during the towing process was (27.06±10.19) t, and the fishing efficiency was (63±19)%. (3) The depth difference between the net position and the mass center of the krill swarm had an extremely significant influence on fishing efficiency (<0.001), and when the two were in good agreement, the fishing efficiency was high. The net position went up with the increase in the towing speed and a significant correlation was found between towing speed and fishing efficiency (<0.05). The net position went down with the increase of the warp length, but there is no significant correlation between the change in the warp length and fishing efficiency (=0.087). The results of this study will contribute to the effective use of krill behavior in Antarctic krill trawling operations, the improvement of net performance, and improvement of trawling efficiency.