The invention discloses a special tool for deep water test depth correction. The tool comprises an upper airtight buckle used to connect a pup joint upper pipe string, an upper pup joint body, an integrated lifting lug, a lower thickened pup joint body, and a lower airtight buckle used to connect a pup joint lower pipe string. The upper pup joint body and the lower thickened pup joint body are of an integrated structure. The integrated lifting lug sleeves the upper pup joint body and is locked by a jackscrew. By adopting the structure, under deep-water sea conditions, a depth correction cable can be fixed to a test pipe string so as to lift and sink with the test pipe string during conventional semi-submersible platform deepwater test pipe string depth correction. Therefore, large error caused by test pipe string depth correction data is avoided, the safety of the test pipe string is ensured, and the risk and the occurrence of accidents are reduced. In addition, the tool has the advantages of simple operation, convenient maintenance, and the like.