A novel wavelength-division demultiplexer which is based on photonic crystal fibers (PCFs) with hybrid light-guiding mechanism has been proposed. Different from the traditional PCFs, hybrid light-guiding PCFs share the properties of both the index-guiding PCFs and the bandgap-guiding PCFs. The proposed wavelength-division demultiplexer can be used in the coarse wavelength-division multiplexing system. The proposed wavelength-division demultiplexer consists of three cores. High-index materials are filled into the circle of air holes around the three cores. Because the material’s indices are different, the PCF operates by a hybrid light-guiding mechanism. According to the coupled-mode theory, the coupling happens when the propagation constants of two adjacent cores are equal at a particular wavelength λ0. There are two corresponding wavelengths, so two beams of light with different wavelengths can put out in different cores if choosing the appropriate parameters of PCFs. By full-vectorial finite element method (FEM), the properties of PCF are be analyzed and the coupling lengths for different-wavelength lights were calculated. Numerical simulations by beam propagation method demonstrate that it is possible to obtain a 4.3 mm-long wavelength-division demultiplexer which can separate two lights with wavelength 1.31 μm and 1.55 μm, respectively.