The invention discloses a high-quality imaging method of a spectral imaging system based on a convolutional neural network, and belongs to the field of computational photography. According to the invention, the hyperspectral image imaging process and the reconstruction process are considered together; in the reconstruction process, the spatial correlation and the spectral correlation between images are respectively considered, the residual error learning is used to accelerate the training speed and convergence speed of the network, the coding network is optimized while the network is reconstructed, and a GPU is used to complete the optimization solution of the whole network. A cuDNN library is used to accelerate the operation speed of the network. The method comprises updating network parameters by using a random gradient descent method; and performing block-by-block processing to complete reconstruction of the hyperspectral image. According to the method, the hyperspectral image reconstruction of the CASI spectral imaging system can be completed with high quality, the high spatial resolution and high spectral fidelity of a reconstruction result are ensured, meanwhile, the efficiency of hyperspectral image reconstruction is improved, and the application range of hyperspectral images is expanded. The method can be used in the fields of manned spaceflight, geological survey, agricultural production, biomedicine and the like.