NOVELTY - A low-carbon oxygen contained oil comprises 500-850 pts.wt. of light oil, 165-335 pts.wt. of methanol, and 50-150 pts.wt. of concentrated formaldehyde concentrated for three times; where the light oil is distilled gasoline, naphtha, stable light hydrocarbon, C5, coal-based liquid oil, light fraction obtained by processing and rectifying by-product coal tar, light oil obtained by catalytic pyrolysis and hydrogenation of the naphtha of oil fraction synthesized by coal, gasoline of coal-based synthetic oil fraction, or light oil obtained by catalytic pyrolysis and hydrogenation of shale oil.    USE - The low-carbon oxygen contained oil is useful for industrial and commercial applications.    ADVANTAGE - The low-carbon oxygen contained oil has good waterproof property. Moreover, it can averagely reduce oil consumption to about 6% in comparison with commercial M15 methanol gasoline through a one-year hundred-kilometer oil consumption traveling test.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is a preparation method of the low-carbon oxygen contained oil comprising dissolving 50-150 pts.wt. of the concentrated formaldehyde concentrated for three times and 165-335 pts.wt. of the methanol in aldehyde/alcohol dissolving kettle; preheating at 40 degrees C by a heat exchanger and pumping into a catalytic rectifying reactor, pumping 500-850 pts.wt. of the light oil at the same time, mixing and heating to near bubble point, raising the substance to enter to a solid acid catalyst bed layer for acetalation, etherification and alkylation; where the substance turns into gas mixture when it leaves from the catalyst bed layer; making the substance pass through a rectifying section filled with stainless material inside to process ripple packing, and distilling off the substance from the tower top, condensing to obtain crude low-carbon oxygen contained oil product containing a little amount of water and methanol; separating 15-20% of the generated water in a middle kettle; and disposing the substance by a dewatering kettle to obtain the low-carbon oxygen contained oil doped with the gasoline of national standard.