In order to supervise the safe operation of the Changma dam, to test design, to validate construction quality and run behavior, to monitor accidents as well as the accumulation of information on evaluation of the dam's future behavior and so on, the deformation and stress-strain of reservoir dam are carried out safety monitoring. Monitoring results show that the development of settlement deformation is still increasing, and have not yet reached a relatively stability according to the development trend of the settlement process. Lateral deformation of the dam isn’t abnormal phenomenon, and accords with the general laws of dam deformation. The compressive stress of dam increases with the increase of the overlay soil layer thickness, the vertical stress is bigger than horizontal or diagonal stress, the measured value and the change process are in line with general law. At present, Changma dam is safe and stable operation.