For nearly three decades, many microcosmic theoretical criterions on impact sensitivity of energetic materials at home and abroad have been suggested by using quantum chemistry calculations and molecular dynamics simulations. In this article, we mainly present some work on thermal decomposition mechanisms and sensitivity criterions of energetic molecules, crystals, and composite materials by our research group. Among them, some studies and criterions on impact sensitivity of energetic crystals and composite materials are reported for the first time. 