This paper deals with a simple and green method to synthesize N-methyl aniline under mild condition. A series of mixed metal salt (Zn and Cu salts) modified kaolin catalysts used in the above-mentioned reaction were synthesized and characterized by a Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM), which exhibited that kaolin was successfully modified by the mixed metal salts. The effect of the reaction time, catalyst, and initial pH on the reaction was recorded by an ultraviolet-visible (UV-vis) spectrum, and the electron spectrum prediction result of the catalyst effect was further confirmed by gas chromatography/mass spectrometry (GC/MS). In addition, N-methyl aniline extracted from the most optimized condition gave a good result in improving the gasoline octane number; however, more research needs to be carried out.