The morphology and stability of solid-liquid interface are closely related to the structures and properties of crystals solidified directionally. It is, therefore, very important to observe and control the interfacial morphology in directional solidification, for fabricating crystals with higher quality. In the present study, the Peltier interface demarcation (PID) method was examined to investigate the morphology and stability of solid-liquid interface in upward continuous casting with various growth conditions.