To investigate the influence of frequency, duty ratio and their interaction on the property of micro-arc oxidation (MAO) coatings qualitatively as well as quantitatively, the MAO coatings on AM60B magnesium alloys in the optimized silicate electrolyte based on orthogonal experiments, investigates the priority of the influence of frequency, duty ratio and their interaction on the performance of MAO coatings, the optimal combination of factors and levels, as well as the significance of their effects on the coatings’ performance with the range analysis and variance analysis based on orthogonal experiments, examines the thickness, microstructures and phase compositions of MAO coatings by using digital eddy current thickness gauge, SEM and XRD, respectively, tests the corrosion resistances of MAO coatings by spotting corrosion test and dynamic potential polarization curve test. The results have shown that the influence of duty ratio on the performance of MAO coatings is greater than that of frequency, and the influence of duty ratio on coatings’ thickness, spotting corrosion resistance and electrochemical corrosion resistance is remarkably significant. The influence of the interaction between frequency and duty ratio is significant on the thickness and spotting corrosion resistance of MAO coatings, especially on the coatings’ electrochemical corrosion resistance. The MAO coatings with best spotting corrosion resistance were fabricated with frequency 1800 Hz and duty ratio 40%. While the MAO coatings prepared under the condition of frequency 1800 Hz and duty ratio 20% exhibit the most excellent electrochemical corrosion resistance. Therefore, with the increasing of duty ratio, the greater the coating thickness, the better the spotting corrosion resistance. With the increasing of frequency, the smaller of the surface porosity of MAO coatings, the better the compactness of the coatings and the electrochemical corrosion resistance. Not only the frequency and duty ratio affect the coatings’ performance respectively, but also the interaction between them demonstrates a considerable influence on it. The optimized scheme extracted from this research provides the guideline for further optimization.