The No.4 Building of Yuandong Garden, Longchuan County, Heyuan City, a 22-story building with frame structure is an illegal building to be demolished by blasting.There is a three-story villa 5 m away from the building, whose fence is only 0.5 m away from the building.Therefore, it is necessary to prevent the building from generating backward sliding at bottom.According to the surrounding conditions, the directional collapse blasting demolition method was adopted, and the trapezoidal blasting cut with 13.5 in height was selected.In order to determine the best delay time, ANSYS/LS-DYNA was used to simulate the delay time of 300 ms, 500 ms and 800 ms, and the simulation results showed that 300 ms was the best one.During the detonation, multiple advanced digital cameras, drones camera, high-definition cameras, etc.were used to capture the entire process of building blasting movement and disintegration from different positions and angles.Comparing the numerical simulation and actual blasting results, it was found that they were very close to each other in collapse posture, movement track of observation point, degree of disintegration, shape and range of blasting pile.The accuracy and reliability of the numerical simulation results meet the engineering requirements.