The purified molybdenite were obtained using concentrated sulfuric acid and heating oxidation method, and the samples before and after oxidation were characterized systematically based on X-ray fluorescence spectrum (XRF), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectroscopy. Moreover, its electrocatalytic properties were tested and analyzed. The results show that the average grain size of MoS2 (002) crystal plane direction decreases by 14% and interlayer spacing increases 0.04Å after concentrated sulfuric acid oxidation, and S2− is oxidized into S6+, indicating that layers of Molybdenite can be stripped through oxidation. The reductive peak of potential move forward after oxidation, implying reduction enhancement on p-nitrophenol.