With the progress of science and the development of society, the study of material composition becomes more and more important, and the identification of material composition is mainly to distinguish the spectral information of different substances. Spectrometer is an important optical instrument, which combines the optical method with modern electronic data processing technology, and accurately analyzes the structure, composition and content of the target substance by obtaining its spectral information. At present, it has been widely used in some important scientific fields such as field exploration, material detection and space-borne analysis. In this paper, a new type of spectrometer based on periodic array structure is proposed. The spectrometer modulates the phase of the incident light by using the small hole array structure with the diameter of sub-wavelength. By using the diffraction effect of light, the light intensity distribution of the incident light is directly recorded by Charge Coupled Device1/4 CCD1/4according to different wavelengths. After passing through the diffraction aperture array, the light intensity distribution is recorded again, and the transmittance coefficients of the diffraction aperture array for different wavelengths are obtained respectively. Finally, the transmittance matrix of diffraction aperture array for incident light is obtained, and the spectral curves of different incident light can be obtained by data processing algorithm according to the transmittance matrix. The main optical device of the spectrometer is diffraction aperture array, which is a metal film coated on a transparent substrate made of resin material. A series of aperture arrays with diameters of 2-78 microns and 10*10 are processed on the metal film by micro-nano processing technology. Any aperture has different diameters, and the apertures are periodically arranged on the metal film. By using diffraction effect, the incident light with different wavelengths will produce different light intensity distribution on CCD. Combined with data processing method, the incident light can be obtained. Compared with the traditional spectrometer, the new spectrometer has no moving parts in the system, which improves its stability, and has the characteristics of fast data processing, small size, low cost and high spectral resolution. In this paper, the theoretical analysis, simulation and experimental verification of the new spectrometer are carried out. The results show that the new spectrometer has obvious advantages compared with the traditional spectrometer and has broad application prospects. © 2020 SPIE.