Objective A new method of surface strengthening by ordinary high-speed Electrical Discharge Machining ( EDM) hole processing tool was described. Methods Sediment layer reinforced by tungsten carbide on surface of 45steel could be obtained based on the theory of electric spark deposition by changing the polarity in the air dielectric. This paper analyzed the influence of various process parameters on the sediment quality from three aspects of the roughness, thickness and micro sedimentary defects. Results 7 A and 80 μs pulse width was chosen to get the optimal sediments of comprehensive quality, its thickness could reach 35 μm and its hardness was 1000HV without visible flaws in the sediment layer. Conclusion The D703F high-speed EDM hole processing tool could generate sediment layer through changing its polarity and get optimal sediments layer by appropriate adjustment of processing parameters.