Abstract: Based on the first–principles method of density functional theory(DFT), the three structures of N–methane hydrate after the introduction of Na⁺ and Cl^– were studied, and their structure, electronic and optical properties were obtained. The results are as follows:1) The volume of the three high–symmetry structural positions and the variation in the edge length of their water cages are significant., and the structure of water molecules and the hydrogen bond length of water cage will change significantly with the introduction of Na⁺ and Cl^–, which is mainly caused by the ion hydration, and the electron density difference distribution also shows this; 2) The presence of Na⁺ and Cl^– can enhance the stability of the water cage structure, with the S–position being the most stable, having the lowest binding energy of –1.082 eV; 3) The energy gap of N–methane hydrate changes from 5.397eV to 0, and the conductivity is greatly improved, which is caused by the introduction of Na⁺ and Cl^–; 4) The slight shift of the N–methane hydrate's density of states toward the lower energy region suggests a lower energy state and higher thermodynamic stability, which favors its formation. This conclusion is further supported by differential charge density analysis and charge population calculations, both of which demonstrate the enhanced hydration capability of Na⁺ compared to Cl^–; 5) The X–ray diffraction patterns of the NaCl–modified N–methane hydrate exhibit nine additional diffraction peaks compared to the pristine hydrate, along with intensity variations in existing peaks. These changes suggest structural modifications induced by electrostatic interactions arising from ion hydration, while no significant changes were observed in other optical properties.