Abstract: To research the failure characteristics of building and non-structural element on the extraordinarily fire explosion accident (“8·12”) which happened in Tianjin Port, and to provide reference for safe distance of urban disaster prevention planning, through detailed site investigation and related numerical calculation, a new formula of the shock wave overpressure which can be used in near field and far field were proposed. Through the comparison and validation with the actual damage, and according to the explosive power and the distance from explosive source, as well as the casualties, the damaging range was divided into different damage levels, and it could supplement and revise the urban disaster prevention planning.