House has significant structural time-varying properties in the process of storey-adding. In order to ensure the safety of storey-adding reconstruction of an industrial workshop,the paper made reasonable construction sequence based on the actual situation, and divided the construction process into different stages by time point of structural dismantlement and simulated the construction process of structure by birth-death element technology of finite element analysis software MIDAS.It obtained the internal force variation rules of structure and danger point during the construction,and proposed corresponding security control measures.