The spatial evacuation efficiency of a settlement reflects the ability of the settlement to rapidly evacuate and shelter after an earthquake disaster. As the key index of evacuation efficiency, it is important to accurately predict the evacuation distance and evacuation probability of residents traveling through the evacuation path. Currently, the evaluation of evacuation efficiency is mostly focused on the calculation of the shortest path distance from the building to the emergency shelter, or the evaluation of multiple factors affecting the evacuation efficiency, such as building density and building width. However, many earthquakes and researches at home and abroad have shown that the collapse of buildings is the main factor affecting the evacuation distance of residents after an earthquake. As the evacuation vehicle for residents to evacuate from buildings to emergency shelters, a method is needed to predict the effect of road blockage caused by building collapse on the evacuation distance. In this paper, we analyze the process of the impact of building collapse on roads, combine and improve the results of existing research, and propose a calculation method for quantitatively evaluating the impact of building collapse-induced road obstruction on the efficiency of emergency evacuation from a residential space.