Abstract: The semi-solid billet of 6061 alloy was prepared by electromagnetic semi-continuous casting technology and the reheating experiments were carried out. The influence of holding temperature and time on quenching microstructures after reheating was studied by observing the microstructures of ingot and reheated billets. The results showed that 6061 ingot with fine and uniform equiaxed grain structure can be obtained by electromagnetic semi-continuous casting. The microstructure evolution is accelerated with the increase of holding temperature during reheating. Too high holding temperature is not good to the property of formed parts because of the coarse grain of quenching microstructure. The quenching microstructure turns out to be more spherical because the α-Al spheroidizes continuously with the increase of holding time, but the grain size increases obviously. The fine and uniform grain structure can be obtained by reheating at 610~630°C for 10~15 min.