The efficiency of gas turbines depends on the gas turbine working temperature. Single crystalblades are being applied more often than equiaxed blades in gas turbine engines, to increase the turbine inlettemperature, resulting in enhanced turbine engine efficiency. Single crystal blades endure creep conditionsat high temperature better than polycrystal blades because the single crystals do not include grain boundaries. The single crystal process is a breakthrough technology, however, production yield is relatively low comparedwith polycrystal, and their mechanical properties depend on the crystallographic orientation of the singlecrystals. In this study, a thermal simulation model, the 3D cellular automation-finite element (CA-FE), wasused on the single crystal process with the Bridgman method. The simulation model was well expected, byanalysis of the microstructure and EBSD, on the grain selection in the single crystal process. The evolutionof single crystal grains was analyzed on process of grain selection in start block and spiral selector. Singlecrystal orientation was also investigated to determine the effect of nucleation density, forming in the initialstage of solidification.