Abstract: At present, the concrete dams are monitored by instruments.The results of instrumental observations are important for monitoring of concrete dams but they can not give the stress field and coefficients of dam safety.Besides the instrumental monitoring, it is suggested to conduct the numerical monitoring of concrete dams.The whole dam and whole course 3D finite element simulation computations are carried out from the beginning of construction to dam operation.During construction, the temperature field and stress field of the dam can be given at any time and the stress field of the dam in operation period may be forecasted. If any problem, measures can be taken to avoid accident.The results of instrumental observations are utilized by back analysis.In operation, the numerical monitoring can give the stress field and coefficients of dam safety in which the influences of all the factors in construction and operation are considered．