The work aims to reduce significantly or eliminate the action of galvanic cell in the joint between TA2 and 10CrNiCu steel by depositing the ceramic coating with insulation property on the TA2 surface through micro-arc oxidation (MAO) treatment. Two kinds of MAO coating samples with different thickness were obtained by using different anodizing time. The effect of MAO treatment on corrosion behavior of 10CrNiCu/TA2 galvanic couple in 3.5%NaCl solution was investigated through coupon tests of the galvanic couple samples and electrochemical tests of simulated galvanic couple. The electrochemical test method of simulated galvanic couple with electric insulation properties was also studied. The MAO coating on TA2 surface between TA2 and 10CrNiCu could reduce significantly the action of galvanic cell, and the action of electric insulation increased as the MAO coating thickness improved. When the MAO coating thickness was about 25 μm, the corrosion rate of 10CrNiCu in the galvanic couple sample was only 7% higher than the free corrosion rate. When TA2 treated by entire MAO was connected with 10CrNiCu by short-circuit, the galvanic current of as-obtained couple might be higher than that of 10CrNiCu/TA2 couple with the increase of immersion time. When the MAO sample was added into 10CrNiCu/TA2 couple by series connection to simulate the electric insulation coating, the quality of MAO coating might influence the action of insulation obviously. MAO coating with high quality could inhibit galvanic corrosion significantly. The MAO coating has good electric insulation, and the action of galvanic cell between TA2 and 10CrNiCu can be eliminated completely when the thickness of MAO coating is larger than 25 μm. Wet MAO is obviously different from electric resistance, so the 10CrNiCu/TA2 galvanic couple by series connection with wet MAO is also different from the actual 10CrNiCu-TA2 joint treated by electric insulation and the actual electric insulation joint between different metals cannot be simulated accurately by adding insulation material into galvanic couple by series connection.