UAV (Unmanned Aerial Vehicle) oblique photography has been a newly developed technology in recent years that can construct 3D models quickly. The problems of low efficiency and long period construction in traditional 3D modeling are solved by this technology. This paper researched the 3D modeling technique and analyzed 3D model precision. Combined campus 3D model as an example case, it analyzed the features of 3D model point accuracy, which rendered mean square error of ground detecting point X, Y, Z were 0.068 m, 0.055 m, 0.093 m separately, and detecting elevation point mean square error of building roof is 0.114 m. The results show that the precision of the model proposed by oblique photography can meet the needs of digital city construction.