The invention discloses a method for evaluating blast vibration damage of a building based on 3D laser scanning. The method uses a 3D laser scanning technology to scan the building, obtains comprehensive point cloud data of the building, and performs processing and modeling to obtain distribution patterns, length and width expansions of surface cracks in all load-bearing parts. A new local crack density is defined, and the local load-bearing structural damage of the building is judged by the local crack density. The statistics of each load-bearing structural damage are conducted to obtain theoverall local crack density so as to evaluate the overall damage of the building. The vibration displacement of a geometric centerline of the building can also be obtained at the same time by using the 3D laser line scanning. This method can also measure the continuity of a target object, and can obtain a real-time damage state of the building structure. The method can quickly give structural damage results in the judgment of building damage in the fields of mine, water conservancy and hydropower, transportation and the like, thereby having a broad application prospect.