Abstract: The stress state of concrete dam in the operation period is very complicated while the points of stress- strain observation are very few, thus the safety factor of the damcan not be obtained fromthe observation results of strain meters. Practically, the safety factors of concrete dam in the operation period are given by computation method stipulated in the design specifications which were developed before 1940. The abundant data accumulated in the period of construction and operation can not be reflected in the computation by these old methods. It is suggested to use the whole damand whole course finite element simulation method to compute the safety factors in the safety appraisal of concrete dams in the operation period.