Abstract: The coupling rules of different thickness polyaryl amide-fibers/epoxy and carbon-fibers/epoxy composites radiated by different intensity continuous wave laser beam with wavelength of 1.319 mm were studied by double integrating spheres-photodiode system. The results show that the reflectivity and energy coupling rate of polyaryl amide-fibers/epoxy composite increase while it’s transmissivity decreases when composite thickness increases. The reflectivity and transmissivity increase but energy coupling rate decreases when laser intensity increases. Although the bulk absorption coefficient decreases when composite thickness increases, the change of laser intensity has no effect on it. The carbon-fiber/epoxy composite’s reflectivity increase and it’s energy coupling rate decreases when laser