This paper introduces the important application fields, growth methods and molecular dynamics research methods of GaN. Due to the lack of homogeneous substrate, GaN film growth is limited and the crystal quality is poor. At present, heteroepitaxial GaN has some problems, such as high fault density, large residual stress and uneven thickness. The intermediate AlN buffer layer is used to reduce the lattice mismatch and thermal expansion coefficient mismatch between GaN film and substrate. Meanwhile, the growth mechanism of GaN is not well understood. In addition, molecular dynamics simulation is an effective tool to study GaN growth, which can reveal the growth process of GaN film and the evolution of dislocation from a microscopic perspective. The research of this work can provide reference for the next step of GaN film growth.