Abstract: The simply modeling method of progressive collapse analysis is investigated. The traditional beam element model with absolutely rigid or pinned joints and a solid model are established according to the analysis example which is a 2-storie and 2-bay planer steel frame. The progressive collapse analysis results of the models indicate that the traditional beam element model can not accurately reflect the dynamic effect of the structure because the plastic deformation can not be considered by the idealized joints, and the assessment produced by the traditional beam element model is unconservatice. The analysis results produced by the beam element model introducing a joint mechanical model are very close to that of the solid model of the planner steel frame, while the time consumed by the former is much less than that of the latter. It is recommended to model the structure by a one-dimension element and a mechanical model when carrying on the progressive collapse analysis.