Abstract: Effects of solution temperature on the microstructure and stressrtipture properties of directionally solidified superalloy DZ22 were investigated. The results show that the microstructure changed markedly with increasing solution temperature, i. e. eutectic Y' phases and primary coarse Y' phases are redissolved continuously into- matrix, Ended at 1250-1260℃, and more and finer r' phases are reprecipitated afterwards. The grain boundary morphology changed gradually to"line"form. The dendritic segregation of elements decreased. With increasing solution temperature the longitudinal stress-rupture life at high-and intermediate temperature were enhanced, but the transverse stress-rupture life at intermediate temperature decreased significantly. It is considered that this is associated with the change of grain boundary condition due to exceedingly high solution temperature. The incipient melting temperature of DZ22 alloy was measured to be 1230-1240℃, and may be increased by homogenization at 1150℃. In this paper the principle of determining solution temperature of DS alloys was discussed. It was suggested that the solution temperature of alloys DZ22 selected at 1200-1210℃ is appropriate.