A new free-cutting brass bar with lead free and Sb and Mg was prepared by hot extrusion,which was further treated by quenching and aging.Microstructure of hot extruded and quenched and aged brass was observed by EPMA（electron probe microscopic analyzer） and EDS（energy dispersive spectrometer）,and cutting behavior of the hot extruded brass was examined by the tensile testing and lathe turning.The results indicate that the microstructure of the hot extruded brass containing Sb and Mg is composed of α phase,β phase and metallic compound with Sb and Mg,and it is equivalent to HPb59-1 brass in mechanical properties and is superior to the HPb59-1 brass in corrosion resistance as well as lower in wear resistance and close to brass with lead free from the German in cutting-free performance.The cutting-free behavior of the quenched brass with lead free can be obviously improved after aging treatment as a result of precipitation of uniformly distributed fine metallic compound with Sb and Mg.So,the cutting-free brass with lead free and Sb and Mg can replace HPb59-1 brass in production,realizing circumstance protection with the same economic cost.