The present invention provides a wide-filed spectral imaging system including a laser generator, a wavelength adjustment module, an objective lens, and a single-pixel imaging and a spectral separating module. The laser generator is configured to generate a laser excitation beam. The wavelength adjustment module is configured to disperse the laser excitation beam into a plurality of beams of different wavelengths. The objective lens is configured to focus the plurality of beams of different wavelengths on a sample to excite molecules under test in the sample and generate an emission light. The single-pixel imaging and spectral separating module is configured to generate a series of patterns and modulate the emission light with the series of patterns to generate a diffracted beam. The single-pixel imaging and spectral separating module further disperses the wavelength of the diffracted beam, collects light signals of the expanded diffracted beam, and performs a spectral image reconstruction.