Carbon fiber reinforced polymer matrix (CFRP) composite laminates are increasingly used as structural materials in the aerospace industry owing to their various advantages such as the corrosion resistant property, high specific strength and modulus, high fatigue strength and fatigue damage tolerance, low coefficient of thermal expansion, and light weight. Such an increasing use of CFRP composite laminates raises significant concern over lightning strike impact and necessitates the investigation of their lightning strike damage characteristics. The diameter of an actual lightning arc channel varies from several centimeters to several meters according to reported photographs and ionizing wave analysis. A thorough understanding on the material damage characteristics caused by a lightning strike impact is essential for reducing the lightning strike damage of the composite laminates while maintaining the mechanical properties. There have been numerous studies that investigated the effect of lightning discharges on aircraft composite structures, but the impact of the lightning channel diameter has not been systematically investigated. The goal of this research is to find the correlation between the diameter of electric arcs observed in lightning discharges and the level of damage it causes on CFRP composite laminates.