The invention relates to an unmanned aerial vehicle-mounted laser radar system, which consists of an unmanned aerial vehicle flying platform subsystem, a laser radar subsystem and ground protection and communication subsystems, wherein the unmanned aerial vehicle flying platform subsystem takes an unmanned helicopter as a carrying platform, the laser radar subsystem is used for acquiring three-dimensional spatial information and digital image data and consists of a laser scanner, an IMU (Inertial Measurement Unit), and a high-resolution aerially-photographing digital camera, and the ground protection and communication subsystems are used for protecting flying safety and timely returning working state information of the system. With the adoption of the unmanned aerial vehicle-mounted laser radar system, the patrol efficiency can be increased, the patrolling means is scientific, intuitive and accurate, the potential problems can be timely discovered so as to ensure safe operation and reduce economic losses, and thus, the unmanned aerial vehicle-mounted laser radar system has the characteristics of low cost, simplicity for operating, high accuracy of data and the like.