The invention provides a code aperture spectral imaging system reconstruction method, relates to a method capable of rapidly acquiring a high-resolution hyperspectral image, and belongs to the field of computational imaging. The method provided by the invention is applied to a code aperture snapshot spectral imaging system. Hyperspectral image reconstruction is converted into the optimization of total variation constraints. An alternating direction multiplier method (ADMM algorithm) is used for solving. A conjugate gradient descent method is used to update the hyperspectral image. A soft threshold function is used to update the auxiliary variables of the ADMM algorithm. Iteration is carried out according to the alternating updating policy of the ADMM algorithm to reconstruct the hyperspectral image. According to the invention, the high-resolution hyperspectral image used for code aperture spectral imaging is rapidly reconstructed; the method has the advantages of fast convergence, high reconstruction efficiency and easy parallel processing; and the method is suitable for a code aperture snapshot spectrometer, and can be expanded to be suitable for a spectrometer device based on multichannel sampling.