The invention discloses an integrated compound method for preparing a DLC through ion nitriding and electric arc ion plating. The integrated compound method comprises the steps that S100, ion enhanced nitriding is carried out through utilizing a multi-arc ion plating device, wherein during nitriding, the gas pressure is selected as 0.5 to 5 pa, the nitrogen flow is 20 to 200 sccm, the filament current is 40 to 60 A, the voltage of a filament power supply is 20 V to 100 V, the current of the filament power supply is 10 A to 50 A, the bias voltage of a workpiece is 300 to 1000 V, and according to the depth requirement of a nitrided layer, the nitriding time is 0.5 to 5 h, the nitriding depth is 10 to 50 microns, and the microhardness is hv1000; and S200, after nitriding, the workpiece is directly coated, wherein during coating, the arc current is 30 to 80 A, the bias voltage of the workpiece is 0 to 100 V, and according to the depth requirement, the coating time is 20 min to 100 min, and the coating depth is 0.5 to 3 microns.