We developed a real-time crystal growth and load-cell model that works under the same growth conditions as the actual crystal pulling process for REBa2Cu3O (RE123) single crystal. Comparing the load cell signal in the model and an experimentally obtained actual load cell signal, we can adjust crystal growth coefficient parameters of the growth model to minimize the difference between these two load cell signals. Finally, it was confirmed that both the model crystal shape and the model load cell signal were in good agreement with an actual value in the initial growth stage.