The effect of melt overheating treatment on the solidification segregation of M963 cast Ni-base superalloy has been studied. The results show that the melt overheating treatment has little effect on the segregation of Al, Co and Ni; and the melt treatment at 1 923 K for 5 min caused an increase in segregation of Ti, Nb and W and a decrease in segregation of Mo and Cr obviously. It is suggested that the change of segregation is attributed to the change in the melt structure of the M963 superalloy.