The test uses ZM6 magnesium alloy as the experimental material，the micro-arc oxidation powersupply uses a constant pressure mode，and the performance of the micro-arc oxidation film layer is performed by ascanning electron microscope ( SEM) ，X-ray diffractometer ( XＲD) ，Vickers hardness tester and electrochemicalworkstation. The effect of different concentration of Na2WO4 additive in silicic acid system on the surfacemorphology，phase composition and corrosion resistance of micro arc oxidation layer of ZM6 magnesium alloy wasstudied. The experimental results show that the addition of Na2WO4 can effectively improve the surface morphologyand properties of the films. With the increase of Na2WO4 concentration，the corrosion resistance first increased andthen decreased. When the Na2WO4 concentration is 1 g /L，the film quality and corrosion resistance are the best;the film phase is mainly composed of MgO，Mg2 SiO4 and a small amount of WO3; the self-corrosion potential is－ 1. 482 247 V，and the corrosion current is 0. 146 μA.