The invention specifically relates to a nanometer hybrid lubricant, which belongs to the technical field of well drilling in the petroleum industry. The lubricant contains graphite oxide and a biquaternary ammonium salt compound, wherein the cation part of the biquaternary ammonium salt compound is as shown in a formula (I) which is described in the specification. The invention also provides a preparation method for the nanometer hybrid lubricant and the lubricant prepared by using the method. The invention also provides application of the lubricant as a treating agent for a drilling fluid in oil-gas drilling, and an oil-based drilling fluid containing the lubricant and application thereof. The lubricant provided by the invention is a nanometer hybrid lubricant. As the lubricant is applied to the oil-based drilling fluid, the lubrication coefficient of the drilling fluid can be substantially reduced, the lubrication performance of the drilling fluid can be improved, and small influence is posed to the rheological properties of the drilling fluid. The lubricant prepared in the invention has excellent heat stability and is applicable to high-temperature operation.