The invention discloses a voltage step micro-arc oxidation method: after surface preprocessed part and a counter electrode are respectively connected with output ports of a power source and then are steeped into a micro-plasma oxidation electrolyte, a low voltage delta U is used as start voltage and applied, afterward the voltage is increased in a step way, when reaching the peak value delta

, the voltage is maintained, until a total process time t is finished. The method of the invention not only can effectively weak the impact to the power system caused by a current pulse which isproduced at the instant when the voltage-control micro-plasma oxidation is started, obviously decrease the request to the nominal parameter of the micro-arc oxidation power source, and save the manufacture/procurement cost of the micro-arc oxidation power source, but also can improve the electric efficiency and reduce the thermal losses. Moreover, when the micro-arc oxidation method provided by the invention is used, the membrane effect can be also obviously improved, and obtains a smoother, evener and more compact ceramic membrane can be obtained.