The energy of solution to linear wave equation is, roughly speaking, distributed equally inside and outside the light cone when time is large. This phenomenon, known as partition of energy, has already been applied to the study of blow-up of nonlinear wave equations. In this talk, we will present a generalized version in the framework of microlocal analysis for a large class of dispersive equations, including Schrödinger equation, (half-)Klein-Gordon equation, and linearized water-wave equations. A heuristic explanation and a formal proof will be given in the end of the talk.