Abstract: White cast iron was prepared by melt-complex modification method during the process of casting.The influences of complex modification and carbon content(2.2%-3.2%) on microstructure and mechanical properties,and the effect of carbon content on the modification effect were investigated by using optical microscopy,quantitative carbide analysis,hardness test and impact toughness test.The results show that with increasing the carbon content,the microstructure of the white cast iron transformed from divorced eutectic cementite plus pearlite to pearlite plus bulk ledeburite.Additionally,complex modification could improve the morphology and distribution of carbide significantly.The carbide net was partly dismissed after complex modification.However,with the increase of carbon content,the effect of the complex modification declined.The hardness and impact toughness both increased after modification.