The invention provides a regional power grid photovoltaic power prediction optimization method and device. The method comprises the steps of acquiring historical operation data, station prediction meteorological data, station prediction data, station actual measurement data and operation data of a photovoltaic power station in a regional power grid; establishing a simplified photovoltaic-electricconversion model of the photovoltaic power station according to the historical operation data; obtaining a photovoltaic power prediction total error according to the station prediction data and the station actual measurement data; obtaining equivalent prediction data according to the simplified optical-electric conversion model, the station prediction meteorological data, the station prediction data, the station actual measurement data and the operation data; obtaining errors caused by each key link of photovoltaic power prediction of the photovoltaic power station according to the photovoltaic power prediction total errors and the equivalent prediction data; and optimizing each key link of photovoltaic power prediction according to errors caused by each key link, so that the power prediction precision can be effectively improved.