The invention provides a carbon material for heavy metal adsorption and a preparation method and application thereof. By grafting an oxygen-containing group on a carbon material and combining the oxygen-containing group with a phosphorus-containing group, more than 90% of heavy metal ions can be removed in an acidic environment without adjusting the pH value. The method comprises the following steps of oxidizing the carbon material: adding concentrated sulfuric acid into the carbon material, stirring and adding potassium permanganate, adding ice into the solution for quenching, cooling, dropwise adding hydrogen peroxide until the solution becomes bright yellow, stirring, centrifuging, and washing until the pH value is not changed to obtain the carbon oxide material, and performing the phosphorylation of the carbon oxide material: taking the carbon oxide material, phosphorous acid and phosphorus trichloride, stirring, heating, mixing, cooling, adding water after cooling, heating to a certain temperature, refluxing for a certain time, carrying out suction filtration, collecting solids, adding water, heating to a certain temperature, refluxing for a certain time, cooling to a certaintemperature, filtering while the solids are hot, collecting the solids, and washing until the pH value is not changed to obtain a phosphorylated carbon oxide material.