Abstract Laser melting and subsequent heat-treatment have been used to modify the pearlite ductile iron coated with Buckytubes. The hardness of the samples can reach HRC65. Studies through SEM indicated that the main structures are martensite and net carbide. Meanwhile, the number of nodular graphite decreases obviously. Circular structures composed of martensite and carbide are found around nodular graphite. A new phase with regular shape has been observed. The new phase is devoid of Fe, Mn, Cr, Ni, Cu and its formation relates with the martensitic transformation.