The heat treatment process is a necessary part after solidification in single crystal superalloy. The microstructure after heat treatment affects the service performance significantly. However, heat treatment experiments are time-consuming and costly. To investigate the microstructure evolution in Ni-based superalloys during heat treatment, a multicomponent multiphase-field model is established for the heat treatment process in Ni-based single crystal superalloys. The Thermo-Calc database is used to calculate kinetic and thermodynamic parameters in multicomponent superalloy. The microstructure evolution will be discussed according to the simulation results and the effect of cooling rate and heat treatment time will also be explored. Finally, the design of heat treatment process will be considered.