Automatic tensioning system for protective net

The utility model discloses an automatic tensioning system for a protective net. The automatic tensioning system comprises a winch transmission device, a block sleeve and a bayonet lock, the winch transmission device comprises a winch wheel, a driven wheel and a winch transmission rope, the winch transmission rope is parallel to the protective net fixing rope, a bayonet lock is fixed to the winch transmission rope, a bayonet lock elastic piece capable of being folded under the action of external force is arranged on the side face of the bayonet lock, a plurality of block sleeves are arranged on the winch transmission rope in a sleeving mode, and the block sleeves correspond to blocks of the protective net one to one; the block sleeve is fixedly connected with the hook of the protective net of the corresponding block, and a plurality of block sleeve limiting devices are arranged on the protective net fixing rope to prevent the block sleeve from being separated from the corresponding block. The automatic tensio