In this study, a three-stage folding blast demolition planning of buildings was introduced by using Key Element Index (KI) which can numerically evaluate the contribution of a column to the strength of buildings. In addition, to improve the efficiency of blast demolition, time interval between the second and the third blast was selected according to the impact load of the upper part of the building acting on the lower part after the second blast. The Adaptively Shifted Integration (ASI) - Gauss code which can stably perform non-linear structural analysis was used as a numerical code to simulate and investigate the blast demolition plan. From the numerical results, the relationship between the number of removed columns and the height of remains, the scattered distance after blast demolition were investigated to see the effect of time interval between the blasts on the efficiency and safety of the folding blast demolition of buildings.