A novel hierarchically N-doped porous carbon material (NP) has been prepared using potassium citrate as the carbon source and urea as the nitrogen source by a facile one-step carbonization method. The resulting NP materials possess two important characteristics: (1) They have abundant nitrogen contents (up to 11.03%) and (2) they exhibit, in relation to porous carbon without urea doping (narrow micropore size), a wider mesopore size. The NP materials exhibit an excellent acetone adsorption capacity; a highest value of 1058mgg(-1) (15 degrees C) was provided by carbon material prepared in the case of urea/potassium citrate=1 and 800 degrees C, which is 158.6% higher than that of the N-free material. The total pore volume, especially the mesoporous volume, was the key factor to determine acetone adsorption under relative high pressure due to the presence of a multilayer adsorption based on adsorption isotherm models. Meanwhile, nitrogen functional groups promoted adsorption process at relative low pressure, and density functional theory results further confirm nitrogen-containing functional groups enhance adsorption interaction between carbon surface and acetone molecule through the hydrogen bonding interaction. This study paves a new way to develop a novel hierarchically N-doped porous carbon with controllable well-developed porosity for the adsorption applications.