The collapse of structures caused by earthquakes causes catastrophic loss of life. Such collapse is typically caused by the inability of the structural system to redistribute its loads following the failure of one or more structural members to carry gravity loads. To study its mechanism in detail, numerical simulation is a significant method to reproduce the whole process of collapse in structural level. However, the traditional method was based on macro factors for collapse analysis and energy change in collapse process was less analyzed before, in fact, the kinds of energy components change with earthquake acceleration inputted and therefore it is necessary to analyze structural whole collapse process in terms of energy method. A three-dimensional computer simulation of the collapse of a real steel frame structure has been conducted using the LS-DYNA computer program in this paper. The responses and kinds of energy components of the structure under seismic loads are analyzed at different ultimate plasticity strain values and the strain energy change rate method for evaluating structure collapse is proposed in this paper. At last, the three main collapse patterns of structures are proposed.