The assessment of building’s vulnerability is part of debris flow’s vulnerability research, which plays an important role in debris flow risk assessment and risk management for cities and towns threatened by debris flow. This paper has reviewed the development of vulnerability assessment of buildings since the 1990s. At present, there have been many empirical vulnerability curves for buildings impact by debris flow. However, most of them are proposed for typical buildings and the mechanism of damage model is still unknown. Therefore, it is advisable for researchers to calculate the vulnerability of buildings by using dynamic methods and conducting impact experiments. But the weak study of debris-flow impact force and complication of the vulnerability of building hamper the application of dynamic and experimental methods. Thus, the empirical static method will still be available to calculate the vulnerability of building in the near future，and to seek the dynamic mechanical solution of building vulnerability may also be pursued by debris flow researcher. Besides, relative achievements in other hazard field, such as rockfall, earthquake, snow avalanche, etc., should be introduced in debris flow vulnerability study, so as to enrich the way to study building vulnerability. In older to calculate the vulnerability of occupant in the buildings, we proposed the event tree model based on time probability and condition probability. Finally, an effective method combined by structural vulnerability and personal vulnerability should be presented.