A light guide plate (LGP) and LGP-based flat fluorescent panel (FFP) provides consistent light source for FFP to output consistent and high luminance light source for upgrading general light emitting efficacy to facilitate subsequent use of the light source by expanding incident angle for creating a scattering belt to destroy the total reflection of the light source passing through the scattering belt thus to avail better deflection to reduce light and shade stripes created in subsequent reflection.