A concise method of estimating high-reflection range for layered media composed of finite periodic unit is presented. Based on the Floquet theorem, the photonic bandgap properties of periodic layered media are analyzed, and the wavelength range of high-reflection region for periodic layered media is discussed. The relation between high-reflection region of layered media and forbidden band of the periodic unit is discussed. Numerical results show that the center wavelength of high-reflection region coincides with the one of the forbiddan band of periodic unit. Furthermore, as the periodic unit number of layered media is increased, the depth and width of high-reflection region become close to those of forbidden band of the periodic unit. Finally, the variations of photonic bandgap properties of periodic layered media with respect to the incidence angle and polarization have also been discussed.