Abstract: The necessity and design principles of safety monitoring for Middle Route Project of South-to-North Water Diversion as well as the layout of safety monitoring instruments and facilities are expounded in combination with the practical monitoring conditions in water filling trial and emergency water transfer periods. The engineering safety of the project is evaluated through the analysis of monitoring results. It is concluded that the normal operation of the project would not be affected if the problems in channel projects, large scaled buildings, cross-channel structures discovered in the water filling test period are analyzed and solved. Finally, some suggestions for safety monitoring during operation period of the Middle Route Project are proposed.