Abstract: As a new type of directed-energy weapon, high-energy laser (HEL) systems demonstrate significant advantages in counter-unmanned aerial vehicle (C-UAV) operations, including rapid response and high cost-effectiveness. This study takes the small quadcopter as a typical research subject to conduct modeling, simulation, and quantitative analysis of HEL damage effects.The research systematically reviews the state-of-the-art in HEL-based C-UAV technologies. Subsequently, a damage assessment model is established, incorporating key modules such as laser atmospheric transmission, irradiation response calculation, and damage degree evaluation. Through vulnerability analysis of UAV systems, critical damage components are identified, enabling the development of a thermo-mechanical coupled laser damage assessment model. Finally, numerical simulations are performed to evaluate damage effectiveness under various operational parameters. The simulation results demonstrate that the damage time exhibits strong correlations with both engagement distance and laser power density. Specifically, the damage time decreases with reduced operational range and increased power density.