The invention provides a drilling fluid containing epoxy resin microspheres which are 10-500 [um]m in particle size and account for 1-10 wt% of the drilling fluid. The epoxy resin microspheres are prepared through the following steps: uniformly dissolving epoxy resin, a diluent and a curing agent to form an oil phase, dispersing the oil phase in a water phase to which a dispersing agent and a dispersion additive are added, wherein the particle size is controlled through oil-to-water ratio, stirring speed and concentration of the dispersing agent, and when the oil-water emulsion is uniformly dispersed, increasing the temperature to cure the epoxy resin, and centrifugally drying the mixture to prepare the drilling fluid. By means of addition of the epoxy resin microspheres to the drilling fluid, the drilling fluid is improved in lubricating property. The epoxy resin microspheres are better than hollow glass micro-beads and polystyrene microspheres in application effects.