The invention discloses a preparing method of Nitrogen-doped carbon nano-material modified by metal cobalt. The preparing method comprises the first step of adopting Ethylene glycol-bis-(2-aminoethylether)-N,N,N',N'-tetraacetic acid or ethylenediaminetetraacetic acid as a carbon source and adding the carbon source into a beaker; the second step of stirring the carbon source and using a nitrogen source to adjust the ph value of a solution to be neutral till the carbon source is completely dissolved; the third step of adding water into cobalt nitrate or cobalt acetate to dissolve cobalt nitrate or cobalt acetate, putting dissolved cobalt nitrate or cobalt acetate into the solution of which the pH value is already adjusted; the fourth step of stirring the solution and afterwards again adjusting the pH value to be neutral, and putting the prepared solution into a rotary evaporator to spin out moisture; the fifth step of placing the solution to an electrothermal blowing dry box to dry the solution and obtaining a solid body; the sixth step of grinding the obtained solid body into fine powder and placing the fine powder into a porcelain boat, under the condition of the protection of nitrogen, placing the porcelain boat in a vacuum tube type high-temperature sintering furnace to be subjected to heating and roasting to prepare the Nitrogen-doped carbon nano-material modified by metal cobalt. According to the preparing method of the Nitrogen-doped carbon nano-material modified by metal cobalt, the steps of synthesis of carbon nano-materials, doping of nitrogen, and modification of metal ion cobalt are integrated into one, thus the obtained catalyst is large in superficial area, stable in structure and property, and is applicable to heterogeneous catalysis such as epoxidation of alkene.