The invention discloses a horizontal expansion device for a Euphausia superba trawl net. The horizontal expansion device comprises a vertical 'V'-shaped curved net plate which comprises an upper cross rope plate, a front flow guide plate, a rear flow guide plate, a towing warp pulling plate, inter-plate reinforcement plates, a lower cross rope plate, a trawling iron attachment plate, trawling iron, a middle towing warp plate, a front main panel, a rear main panel, an upper balance plate, pulling holes of the upper cross rope plate and pulling holes of the lower cross rope plate. The horizontal expansion device is characterized in that an aspect ratio of the 'V'-shaped curved net plate is larger than or equal to 2.7; the towing warp pulling plate which is welded to the middle towing warp plate is in longitudinal arrangement and provided with five towing warp pulling holes in longitudinal array, and the towing warp pulling holes are connected with towing warps through towing warp shackles; the rear side of the upper cross rope plate of the 'V'-shaped curved net plate is provided with six pulling holes of the upper cross rope plate, the rear side of the lower cross rope plate is provided with six pulling holes of the lower cross rope plate, and the pulling holes of the upper cross rope plate and the lower cross rope plate are in corresponding connection with an upper cross rope strand and a lower cross rope strand through cross rope shackles. The horizontal expansion device is especially suitable for low-speed Euphausia superba trawl nets.