The concept and work process of laser relay mirror technology are analyzed, and the model of laser relay mirror system is established. The effect on 1 km altitude target of the 100 kW, with 10 km altitude, launching, receiving, secondary launching telescopes with 0.5 m outer diameter and 0.2 m inner diameter telescope solid laser relay mirror system and the conventional high-energy laser system with the same parameters under the Hufnagel-Valley 5/7 atmospheric turbulence model and the marine environment condition are separately calculated. The relay mirror systems interaction time on the target is longer and with the extreme power density damage threshold standards for conventional laser system in relevant literature and the relay mirror system are 4000 W/cm2 and 800 W/cm2. The coverage range of the convention high-energy laser system is 1.38 km, and the coverage range of laser relay mirror system is 12.2 km.