Abstract: The difference in the method between automatic monitoring and manual observation for damdeformation monitoring system was indicated. It discussed that the build method of automatic monitoring systemfor wire alignment in dam. Explained it was unadvisable to try to use bidirectional wire alignment for monitoring vertical displacement up to now. It showed by analysis that the accuracy of wire alignment systemwould be obviously lower when the ended point extended, and the extended disposal of the ended point should avoided when the wire alignment longer. The liquid multi- point leveling with bio- metal tube mark using method of difference measurement were a agility and convenient automatic monitoring system for high accuracy vertical displacement of dam. The accuracy of inclinometer and pendulum was showed by comparison and analysis, the idea that trying to replace pendulum using inclinometer was unadvisable.