A novel slow light photonic crystal waveguide is proposed by introducing two additional adjacent holes into the single line-defect structure. Influences of the boundary row shifts and the additional holes′ distance on the device performances are investigated in detail. Compared with the boundary row shifts method, a better slow light property can be obtained by modifying the distance of two additional adjacent holes. Numerical results demonstrate that the group velocity is reduced to 0.03c (c is the light velocity in vacuum) under nearly the same operational bandwidth.