Abstract: Aniron-buckytube composite material was fabricated by direct melting. Rock-well hardness and microstructure of the composite material after quenching were investigated. Experimental results show that Rockwell hardness of the iron-buckytube composite material can peak HRc65 after adapt able heat treatment and it is harder than common irongraphite alloy by 5～10 HRc under the same condition. The analysis of microstructure indicates that there exists a kind of carbon-rich white phase that emerged in martensite. Differential thermal analysis(DTA) and high resolution transmission electronic microscope(HRTEM) observation results indicate that the buckytube is stable up to 1400℃, so it can be retained in the composite and it plays animport antrole in strengt hening mechanism.