In the last decade because of the frequent occurrence and great harm brought by the progressive collapse of structures, this problem has attracted increasing attention in the engineering field and has become a hot research issue worldwide. Progressive collapse is defined as a situation where the local failure of a primary structural component leads to the collapse of the whole structure. A safe and robust structure is able to bear the required loads to prevent complete collapse. Researchers have suggested a number of ways to ensure that buildings of significant size can absorb local damage and resist progressive collapse. However, the source and magnitude of the loads may differ, so it is impossible to design and construct structures that can guarantee absolute safety. Although much work has been done in the field of structural robustness, the term used for structural property prevents progressive structural collapse and is still in the exploration stage. So far, there is no clear definition or accepted parameters to quantitatively evaluate structural robustness. In this study, we describe the progressive-collapse resistance robustness of a frame structure and propose a target-oriented component vulnerability coefficient in combination with an internal force feature of the frame structure during the collapse process. Additionally, we improve an existing structural robustness coefficient. Furthermore, we verified the practicability of our proposed method by computing a finite element model of a reinforced concrete frame structure using the finite element analysis software, SeismoStruct V6.5. Our results show that structural robustness is relative and can be enhanced by reducing the member vulnerability coefficient of important columns. Under the same load, the vulnerability coefficient of the frame columns can be segregated as the middle, side, and corner columns, and the member importance coefficients have the opposite values. Components with large vulnerability and important coefficients should be protected to ensure structural robustness.