Abstract: This paper aims at analyzing the effect of solution temperature and preheat treatment on residual eutectic of blades of the first-generation directional solidification nickel-based superalloy DZ408, in order to discuss the effect of different heat treatment on residual eutectic and mechanical property. The results suggest that the amount of the residual eutectic decreases with the solution temperature increasing and staged preheat treatment. The stress-rupture property at intermediate temperature decreases when the solution temperature reaches the incipient melting temperature. The high temperature stability is influenced by more residual eutectic. According to the analysis results, a new heat treatment rule was put forward.