The invention provides a photovoltaic power station theoretic output assessment method based on actually-measured meteorological data. The method is characterized by converting actually-measured horizontal plane irradiation intensity into photovoltaic component inclined plane irradiation intensity through a physical method, and converting environment temperature into panel surface temperature; and through overall consideration of factors of the position of a photovoltaic power station, characteristics of different photovoltaic assemblies and installation modes and the like, establishing a photovoltaic cell photovoltaic conversion model to obtain theoretical power of the photovoltaic power station. The method, on the basis of the actually-measured meteorological data and through a photovoltaic conversion physical model, can effectively and accurately estimate the theoretic output of the photovoltaic power station to enable actual operation of the photovoltaic power station to have reliable and accurate data basis, thereby ensuring efficient and reliable operation of the photovoltaic power station.