The invention relates to a photovoltaic power station generated power predicting method. According to the technical scheme, five historical days most similar to a day to be predicted are determined from data in the former years according to the situation of the weather forecast of the day to be predicted, eight sets of data, before the time point to be predicted, in the five similar days serve as a training sample, illumination intensity, temperature and the like which are predicted before the time point to be predicted serve as input data, and the predicted power of the time point to be predicted is worked out and obtained through a weighing support vector machine. By means of the similarity computing method and the similar day determining method, the short-term power prediction of a photovoltaic system is achieved through the weighing support vector machine, and the defect of the self-learning ability absence due to the fact that the prediction is carried out only through the similarity day method is overcome.