在一定温度下，研究了Ｑ２３５钢在不同时间条件下热浸铝时镀层的微观结构变化及形成机理。结果表明，浸铝初期，在铝铁界面产生连续的ＦｅＡｌ３薄层；随时间延长，由于斜方晶格Ｆｅ２Ａｌ５相的快速生长，抑制了ＦｅＡｌ３相的进一步形成，使ＦｅＡｌ３相由初期的连续层向非连续相层转变，而Ｆｅ２Ａｌ５相呈不均匀齿状垂直于基体表面生长。通过ＳＥＭ及ＴＥＭ分析了镀层形成机理并提出了镀层的结构模型。 At a certain temperature, the microstructure change and formation mechanism of Q235 steel during hot-dip aluminizing under different conditions were studied. The results show that, at the initial stage of aluminum immersion, a continuous thin layer of FeAl3 is formed at the interface of Al-Fe. With the rapid growth of the orthorhombic Fe2Al5 phase, the further formation of FeAl3 phase is inhibited and the FeAl3 phase changes from the initial continuous layer Non-continuous phase transition, while the Fe2Al5 phase heterogeneous teeth perpendicular to the substrate surface growth. The formation mechanism of the coating was analyzed by SEM and TEM and the structural model of the coating was proposed.