Disclosed are a structure for automatically identifying a predetermined length of a tourniquet, and a method for quickly identifying the predetermined length. The structure for automatically identifying a predetermined length of a tourniquet comprises a box and tourniquets, wherein the box has at least one receiving cavity in which the tourniquets are placed and an opening configured to be passed through by an end of the tourniquets, wherein apertures are formed in the tourniquets at an interval of the predetermined length in a longitudinal direction of the tourniquets, the box is provided with a protrusion configured to cooperate with the apertures during the extraction of the tourniquets, and the apertures are configured to identify the predetermined length of the tourniquets and facilitate tearing off of the tourniquets during the tearing off of the tourniquets.