“How to break through the preparation theory and technology of large size crystal materials” is one of the top ten frontier scientific questions released by China Association for Science and Technology in 2021, which revealing the crystal growth mechanism and breaking through the key growth technologies are the two trends of the development of large size functional crystals. At the atomic or molecular scale, the crystal growth can be described as a thermal activation process with a barrier or an ultrafast growth of crystal without barrier, which is related to the specific system and growth direction. Based on the properties of interface, the smooth interface grown by the way of step expansion, and the rough interface has no obvious solid-liquid stratification, and the growth can be completed by local atomic solidification. The advances of growth theory and technology for the large-size crystals in recent years have been summarized from three aspects: model, technology of growth and its application and the application of molecular dynamics in crystal growth. At present, there are many methods to grow large-size crystals, but the crystal quaility is poor and performance is unstable. The reasons are that the existing technology do not take the micro-mechanism of crystal growth into consideration, and the relationship among crystal growth mechanisms and external factors such as temperature and flow rate are not clear. Using machine learning force field and molecular dynamics simulation method to establish solid-liquid interface and to simulate crystal growth would be an effective way to explore the micro-mechanism of crystal growth.