Based on the equal addition amount of carbon, the effects of MgCO3, CO2 and CO on grain refinement in AM60B alloy were investigated. The results indicated that the average grain size of AM60B alloy reduced from 213μm to 116μm, 90μm and 106μm respectively due to the addition of MgCO3, CO2 and CO. Also, the Vickers hardness, tensile strength, yield strength and elongation of AM60B alloy inoculated by MgCO3, CO2 and CO were all improved in some degree, moreover, AM60B alloy treated by CO2 have the best mechanical properties, followed by CO and MgCO3 in sequence. In addition, supported by SEM, EDS and XRD, the observed Al4C3 particles as a result of the addition of MgCO3, CO2 and CO should be responsible for the grain refinement of treated AM60B alloy.