A slow light photonic crystal coupled-cavity waveguide by introducing two additional holes into the single line-defect structure was proposed. The characteristics of slow light in the coupled-cavity waveguide were investigated with Plane Wave Expansion (PWE) method. Influences of the boundary rows shift and the coupled-cavity length on the dispersion and the group velocity of device were studied. Compared with the boundary rows shift method, the group velocity is reduced to 0.03c (c is the light velocity in vacuum) by modifying the coupled-cavity, meanwhile the effective wavelength range is close to 20nm. Finally, the transmission field distribution under different incident wavelength was analysed with Finite Difference Time Domain (FDTD) method. A good transmission character of the proposed structure is verified by researching transmission field distribution under different incident wavelength in photonic crystal coupled cavity waveguides.