The application of the Unmanned Aerial Vehicle (UAV) are much more prevalent because the UAV is a small plane, cost is not very high, the accuracy of ground control points (GCP) precise information and images can be of high quality. The paper presents a UAVs for Analyzing the Variation of District Building Density in KhonKaen city center. We use analysis the Floor Area Ratio (FAR) and the case study to choose from a cluster of buildings in a radius of one kilometer in the area with the highest density. The size area of the building will be analyzed within the area of road network one block. After we application of the UAV flew photography, we will use information processing program Agrisoft Photoscan to obtain the digital surface model (DSM) and the cloud point to create three-dimensional models illustrate the density of city by use programs CityEngine for find the height of the building and number of blocks in the case study. Applying the UAVs to a real case study shows its Orthophoto, DSM, Cloud Point, 3D Model. The data results, we use created map illustrate district building density and can also be applied in finding the district building density in other areas thus obtain saving both time and budget, there is also a high accuracy. But the limitations of this research must be conducted on the height of buildings in the area.