Abstract: In order to improve the ef fi ciency of photovoltaic (PV) power plant and increase the power generation capacity, it is required to consider various factors for calculating and determining the installation angle of the PV array of power plant. In design of optimal tilted angle of fi xed grid connecting solar PV array, if the total radiation and direct radiation on the horizontal plane could not be used directly, the fi rst thing needed to do is calculating the horizontal solar radiation by using other meteorological data in climatology; then to calculate the total solar radiation of inclined plane by using some radiation models; and then calculate the optimal tilted angle. Through the classifying and summarizing each step of the calculation method, we compare the advantages and disadvantages between different methods, tell calculation methods applicable conditions and recommendations. Finally we compare the characteristics of commonly used photovoltaic power plant design software, and discuss the direction of research and urgent problems of practical application in the optimal tilted angle calculation methods.