The invention provides a laser radar-based intelligent early-warning evaluation method for a power transmission line. The method comprises the following steps: information obtaining of the power transmission line, three-dimensional graphic modeling of the power transmission line, data analysis and judgment, and early-warning and power transmission line security evaluation. High-density and high-precision laser radar point cloud and optical image data on an ultra-high-voltage or high-voltage power transmission line are obtained by a laser radar scanning system carried by a helicopter platform; rapid high-precision three-dimensional measurement and spatial analysis of the power transmission line are achieved; and the analysis is applied to specific inspection and management work, such as sag calculation, line windage yaw check after three-dimensional modeling and line hazard analysis, in power transmission line operation and maintenance. The invention further provides a laser radar-based intelligent early-warning evaluation system for the power transmission line. The system comprises a power transmission line information obtaining unit, a data processing unit, a data storage unit and a feedback unit. According to the system, inspection and early-warning of the power transmission line can be rapidly and accurately achieved; and a safety evaluation report can also be provided to a user.