Hadamard transform spectral imaging technology has high signal-To-noise ratio and the advantage in energy distribution. In recent decades, related works focus on dynamic coding Hadamard spectral imager instead of static coding ones. The latter has great potential value in spaceborne and airborne applications, but the accuracy of its restored spectral image data is poor at present. Therefore, it is necessary to further study the formation mechanism and correction method of errors in static coding Hadamard spectral imager. In this paper, the influencing mechanism and correction method of spectral overflow are studied. Firstly, the imaging and restoration process of the Hadamard coding spectral imager with spectral overflow is mathematically deduced, and the conclusion is compared with the simulated restoration results. Secondly, the simulated results are compared with the experimental data, verifying that spectral overflow is an important source of the error in experimental results. Finally, a correction method for eliminating spectral overflow errors under certain conditions is proposed, and the effectiveness of the method is verified by simulation. This paper can provide reference for the design and data restoration of static coding Hadamard spectral imager. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.