Trigonometric leveling method is often used to connect the height over sea. Error analysis of trigonometric leveling is made. In order to automatically achieve the trigonometric leveling over long distance, an automatic trigonometric leveling system is put forward with the combination of GPS and the automatic target recognition (ATR) techniques in this paper. The primary design of the system prototype including the structure and the software is given. The practical principle tests are also made to prove the system performance. The results indicate that the leveling precision of the system can satisfy the requirement of fourth order leveling.