The phenomenon of spectral splitting in multiple quantum well(MQW)structures composed of one-dimensional photonic crystals is investigated by finite-difference time-domain method. The regularity of splitting is analyzed. It is found that the spectral splitting is induced by the coupling effect of the wells,whose features are determined not only by the well numbers but also by the parameters of barriers and wells. The results indicate that,in the symmetrical photonic MQW structures,each transmission spectrum will split into p different frequencies,where p is the number of the wells in MQW structures. These split spectra are un-folded mutually. In this way,photon confined states can be increased multiplicatively within forbidden band gap region with the maximization of channel density and optimization of effective bandwidth. It may be applied widely in the fields of super dense wavelength division multiplexing for optical communication and the precise optical measurement.