Abstract: This paper reported application of In Situ LPSIRS (linear potential sweep infrared reflectance spectroscopy) technique to get precise spectroscopy information about electropolymerization of 2,6-dimethylphenol on gold electrode in base methanol solution and propose the electropolymerization mechanism under the conditions. From the spectra it has been found that the DMP~- ion was cosumed and PPO polymer was produced during cyclic voltammetry. At the same time, it has been deduced that the methanol in the case probably takes part in the electropolymerization partly. The electropolymerization mechanism of 2,6-dimethylphenol in base methanol is a sequence of alternating ionic and radical steps; the propagation occurs by coupling of two phenate radicals.