Octahydro1,3,5,7tetranitro1,3,5,7tetrazocine (HMX) is one of the most important energetic materials used in various propellants and explosives. The βHMX undergoes a phase transition into δHMX before detonation. The study of the β→δ phase transition in the HMX can deepen our understanding of the sensitivity,detonation process and storing safety of HMX. The crystal structure of HMX,kinetics of the β→δ phase transition and the influencing factors of phase transition were reviewed. The crystal quality of HMX and the solid additive effect on the β→δ phase transition were proposed as the future research direction.