The invention belongs to the field of thermal automatic control, and discloses a power station boiler SCR denitration modeling method based on a selective integration model library. The method comprises the following steps: (a) acquiring parameter values of an inlet and an outlet of a power station SCR reactor for multiple days, dividing the parameter values into a training set and a test set, selecting a learner, and training by using data of the training set to obtain a plurality of models to form a model library; (b) predicting a predicted value at each moment in one day by using the modelin the model library; and (c) t = t + 1, returning to the step (b), after prediction of all moments of one day is completed, updating the model library, taking the updated model library as the currentmodel library, and returning to the step (b) until updating of the model library of the last day in the test set is completed, thereby obtaining the final required model library, namely completing modeling of power station SCR denitration. Through the method, the problems of data screening and parameter adjustment caused by model updating are greatly reduced, the manual action is reduced, and theintelligent degree is higher.