Abstract: To improve the reinforcing effect, a CNTs embedding microst ructure model for CNTs/Al₂O₃ composites was suggested. SWNTs/  Al₂O₃, MWNTs/Al₂O₃ and aligned MWNTs/Al₂O₃ with this kind of microstructure were synthesized by heterocoagulation. Based on the microst ructure and properties analysis, it has been found that the type, morphology and dispersibility of CNTs influence greatly the forming of CNTs embedding microst ructure model. The thin and straight SWNTs are advantageous to the forming of CNTs embedding microstructure model.