The work aims to improve the corrosion resistance of magnesium alloy. A new type of phytic acid chemical conversion coating with high corrosion resistance was obtained based on single phytic acid chemical conversion coatings by introducing metal ions into the reaction solution through the strong interaction of phytic acid. The process formula, microstructure, elemental composition and corrosion resistance of the new coating were analyzed by orthogonal experiment, SEM, EDS and electrochemical method. The optimal process parameters of the new phytic acid conversion coating obtained through orthogonal experiment included 25 g/L of Mn(H2PO4)2, 10 g/L of phytic acid, reaction temperature of 95 ℃ and reaction time of 10 min. The phytic acid coating prepared by the optimal process had a uniform surface and contained fewer cracks, compared with the coating without Mn ions. The EDS results showed that the main elements of the coating were Mg, P, O, Mn, and C. The composition was a complex of manganese and magnesium phytate. The results of the potentiodynamic polarization curves showed that the new coating could greatly reduce the self-corrosion current density (Jcorr=0.337 ) of the magnesium alloy, and the protection efficiency for the magnesium alloy was 96.37%. Adding Mn into the phytic acid conversion coating cannot only reduce the width of the phytic acid coating cracks, but also greatly improve the corrosion resistance of magnesium alloy.