Abstract：Although underwater acoustic secondary positioning technique relating to ocean bottom cable has solved the underwater real-time positioning problem of hydrophones，yet there are still some deficiencies such as no solution point and easy disturbance by other factors. First-break positioning technique for ocean bottom cable is then introduced to remove above deficiencies. First-break positioning technique is described briefly in its principle，and then it is compared with underwater acoustic positioning technique. Finally，quality evaluation criteria for first-break positioning result are given，which include no or few wild values，no obvious whole deviation，-reasonable point interval and comparison with other positioning result.
