The microstructure, surface hardness, thickness and corrosion resistance of the nitrided layer for a low carbon low alloy steel (20CrMnTi) were investigated by the uses of a new quick gas nitriding method based on cold deformation and pressurized gas nitriding. The results show that, the combined cold deformation and nitriding pressure can significantly improve the nitrogen efficiency of the steel. Nitriding layer is mainly composed of Fe2-3N and Fe4N nitrides. When the nitriding pressure is constant, hardness of the nitride layer firstly increase and then decrease with the increase of the cold deformation amount. When the deformation amount is constant, hardness and resistance to corrosion for the nitride layer rise with the increase of nitriding pressure. The nitrided layer of the sample nitrided under 30% reduction, 0.4 MPa for 5 h exhibit the best properties, whose hardness and thickness achieve 825 HV and 310 μm, respectively.