The present invention provides a battery pack housing assembly for an electric vehicle, which is formed of a lightweight composite material to reduce the weight and configured to have a dual laminated structure with a closed cross-sectional area formed by composite molding to absorb impact energy. For this purpose, the present invention provides battery pack housing assembly for an electric vehicle using a plastic composite material, the battery pack housing assembly having an upper cover mounted at the bottom of a vehicle body, a lower housing, and a battery pack received and mounted in the lower housing, wherein the lower housing has a dual laminated structure with a closed cross-sectional area formed by bonding an upper plate and a lower plate, each composed of a fiber reinforced plastic composite material, to absorb impact energy, thus increasing structural stiffness.