[目的]为解决热浸镀锌铝镁合金钢板表面色调单一、易出现黑变缺陷的问题，并满足市场对黑色镀层钢板的高品质需求，开发一种黑色微弧氧化(MAO)表面处理工艺。[方法]采用微弧氧化技术对高耐蚀低铝锌铝镁合金钢进行黑化处理。通过正交试验优化电解液配方。利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、电化学综合测试仪和中性盐雾腐蚀试验，分析了锌铝镁镀层钢板MAO处理前后的微观形貌、组织结构及腐蚀行为。[结果]较优的电解液配方为：硅酸钠9 g/L，氢氧化钾6 g/L，硫酸铜6 g/L。该配方制备的膜层颜色均匀，明度(L*)为38.86，厚度为5～7μm，呈蜂窝状多孔结构，主要由ZnO和CuO组成。电化学测试结果表明，经微弧氧化处理后样品的腐蚀电流密度从5.46μA/cm²降至2.19μA/cm²，经硅烷封孔处理后进一步降至0.24μA/cm²，在中性盐雾试验中的红锈出现时间超过3 000 h。[结论]微弧氧化处理可在Zn–Al–Mg合金镀层表面形成均匀的黑色多孔陶瓷膜，显著提升其耐腐蚀性能；而封孔处理进一步增强了膜层的致密性与防护效果。本研究为高性能黑色锌铝镁镀层钢板的开发与应用提供了可靠工艺路径。

[Objective] A black micro-arc oxidation(MAO) surface treatment process was developed to address the issues of monochromatic appearance and blackening defects on hot-dip Zn–Al–Mg alloy coated steel, while meeting the market demand for high-quality black-coated steel plates. [Method] A black coating was prepared on highly corrosionresistant low-aluminum hot-dip Zn–Al–Mg alloy coated steel via micro-arc oxidation. The electrolyte formulation was optimized through orthogonal experiments. The microstructure, phase composition, and corrosion behavior of hot-dip Zn–Al–Mg alloy coated steel before and after MAO treatment were analyzed by scanning electron microscopy(SEM), X-ray diffraction(XRD), electrochemical testing, and neutral salt spray corrosion test. [Result] The electrolyte formulation was optimized as follows: sodium silicate 9 g/L, potassium hydroxide 6 g/L, and copper sulfate 6 g/L. The coating prepared with the optimized electrolyte exhibited uniform color, a lightness(L*) value of 38.86, a thickness of 5-7 μm, and a honeycomb-like porous structure composed mainly of ZnO and CuO. Electrochemical test results showed that the corrosion current density of hot-dip Zn–Al–Mg alloy coated steel decreased from 5.46 μA/cm² to 2.19 μA/cm² after MAO treatment, and further reduced to 0.24 μA/cm² after sealing with silane. No red rust was observed on the specimen treated by micro-arc oxidation and subsequently sealed, even after 3 000 hours of neutral salt spray testing. [Conclusion] A uniform black porous ceramic coating can be formed on the Zn–Al–Mg alloy coating after micro-arc oxidation, significantly improving its corrosion resistance. The compactness and protective performance of the MAO coating is enhanced after sealing treatment further. This study provides a reliable process route for the development and application of high-performance black Zn–Al–Mg-coated steel plates.