The invention discloses a power grid model data locking iteration method comprising the following steps: enabling the power grid model of each data source to form a power grid full model A through electric power scheduling system network automation influx transition; correcting error data in the power grid full model A; building description data of the power grid full model A, wherein the description data introduces the corrected error data, and locking description is realized; starting the next round of automation influx transition of the power grid model of each data source, thus forming a power grid full model B; updating corresponding data in the power grid full model A according to the locking description of the corrected error data by the description data and the power grid full model B, and carrying out iteration merging of the power grid full models. The invention also discloses a power grid model data locking iteration device and system applying said method; the method uses the locking description of the description data to prevent corrected error data in the power grid model from repeatedly appearing.