Abstract: In response to the challenge of inefficient oblique-photography 3D modeling in emergency surveying and mapping support for the rapid investigation of geological disasters caused by the “8·8” Jiuzhaigou earthquake, this paper proposes an orthographic single-view oblique 3D modeling method based on the study of UAV oblique photogrammetry technology. By combining it with 3D scene construction technology and remote sensing interpretation technology, a comprehensive system for rapid geological disaster investigation using real-scene 3D technology in emergency situations was developed. This system was successfully applied during the rapid investigation of geological disasters after the "8·8" Jiuzhaigou earthquake, providing real 3D models and related information on disasters and damages within the critical 72-hour rescue period. It marked the first time in the history of emergency surveying and mapping support in Sichuan Province that a real-scene 3D model was provided, and it played a critical role in disaster assessment, emergency command and decision-making, as well as post-disaster recovery and reconstruction efforts by relevant authorities. Furthermore, based on the survey results, a series of suggestions for geological disaster prevention, mitigation, and relief were proposed, serving as a scientific basis for the comprehensive prevention and control of geological disasters in affected areas.