The authors proposed an image spectral library based band simulation method. Firstly, the authors clustered the reference image which has the same class composition with the target image by using its pixel spectrum similarity. Secondly, the authors fetched sample from the reference image base on the former cluster image, and then built the image spectral library. Thirdly, the authors fetched the same count of each type of samples to train the simulation model. Finally, the authors simulated the target band of the target image. The experiment results show that: firstly, this method can be more precise to simulate TM blue band, and increase more than 1.2 RMSE value than that of the “Spectral Library-image” model and more than 0.6 RMSE value than that of the “image-image” model. On the other hand, our method is more stable and reliable than the “image-image” and “Spectral Library-Image” simulation model; finally, this method can be successfully applied to the blue band simulation that SPOT and MSS lacked