The　correlation　between　intermetallic　compound　(IMC)　and　interface　bonding　state　of　the　pure　Al/08Al　steel　clad　plate　after　645°C/1h　diffusion　annealing　was　studied　using　the　SEM.　The　results　indicated　that　after　645°C/1h　diffusion　annealing　for　the　pure　Al/08Al　steel　clad　plate,　the　IMC　grew　continuously　along　the　interface　with　the　thickness　of　2-6　μm,　while,　at　some　regions　grew　abnormally　with　the　thickness　up　to　10-30　μm.　Moreover,　some　intrinsic　defects　at　the　interface,　such　as　voids　in　the　abnormally　grown　IMC　and　micro　cracks　along　the　interface　were　observed.　The　voids　were　possibly　caused　by　huge　difference　of　Al　and　Fe　in　diffusion　coefficient,　which　is　known　as　Kirkendall　effect.　On　the　other　hand,　the　micro　cracks　could　be　attributed　to　the　thermal　stress　during　the　cooling　process　because　of　larger　difference　of　thermal　expansion　rate　between　Al　and　Al-Fe　IMC.　The　intrinsic　defects　at　the　interface　of　Al/Steel　could　supply　a　novel　way　to　correlate　the　morphology　of　IMC　and　interface　bonding　strength.　©　2017　Trans　Tech　Publications,　Switzerland.