The invention discloses an automatic hook switching and hauling device and method for a longline. The longline comprises a mine line, a plurality of branch lines arranged on the same, and hooks arranged on the branch lines respectively. The automatic hook switching and hauling device comprises a hauling mechanism, a chute, an electromagnet plate arranged on the chute, and a barrel, circular cutterand clamp sleeve which are arranged on the main line between the hauling mechanism and the electromagnet plate; the left and right sides of the circular cutter are in clearance fit with the barrel and the clamp sleeve respectively; all the circular cutter, the barrel and the clamp sleeve are connected with a support; the electromagnet plate is provided with through holes allowing passage of the main line and the branch lines; the part, close to the electromagnet plate and far away from the surface of the hauling mechanism, of the chute is provided with an opening; a fish collection box is arranged below the opening. The automatic hook switching and hauling device and method for the longline provide a function of carrying out automatic hook switching whether the hooks are empty or not, andprovide high working efficiency and good safety.