The invention provides a micro-pore spectrometer and a spectral reconstruction method. The micro-pore spectrometer is only composed of a light intensity detector and a micro-hole. A to-be-measured spectrum is incident on the micro-hole and is transmitted to the light intensity detector after being diffracted by the micro-hole. The light intensity detector records a corresponding diffraction pattern. After that, the data processing is carried out on the recorded diffraction pattern by using the algorithm provided by the invention, so that the to-be-measured spectrum can be reconstructed accurately. In addition, all spectral components entering the spectrometer can be detected by the detector due to the fact that one part of the micro-hole is completely transparent. Therefore, the micro-porespectrometer has an ultra-wide spectral detection range. The micro-pore spectrometer is simple in structure, extremely low in cost, light in weight, and small in size. The volume of the micro-pore spectrometer can be controlled to be within 1 cm * 1 cm * 1 cm and even smaller. As a result, the micro-pore spectrometer can be widely applied. The micro-pore spectrometer can be loaded on a satellitefor space exploration. The micro-pore spectrometer can also be integrated to a smart phone for pesticide detection, air pollutant detection, water quality monitoring, medical diagnosis and the like.