A hybrid demultiplexer for mode-wavelength division based on nanowire waveguides and one-dimensional photonic crystal nanobeam cavity is proposed. The device consists of a wavelength division multiplexer (WDM) and a mode division multiplexer (MDM), in which the WDM is composed of two one-dimensional photonic crystal nanobeam cavities, however the MDM adopts a silicon-based nanowire waveguide structure. The parameters of the hybrid demultiplexer are calculated using the three-dimensional finite-difference time-domain (3D-FDTD) method. The results show that the four channels of the fundamental mode (TE₀) and the first-order mode (TE₁) at wavelengths of 1570.0 nm and 1573.2 nm can be demultiplexed by this device. The insertion loss and the channel crosstalk are smaller than 0.37 dB and -18.4 dB, respectively. The free spectral range can reach 400 nm. The proposed hybrid demultiplexer can be applied to a mode-division and coarse-wavelength-division multiplexing system.