We present a novel mechanism,which is formed by periodically changing the radii of dielectric rods in the middle row of a photonic crystal, to control and stop light. Using the Bloch theory and coupled-mode theory, the dispersion characteristic of such a photonic crystal coupled cavity optical waveguide is obtained. We also theoretically demonstrate that the group velocity of a light pulse in this system can be modulated by dynamically changing the refractive index or radii of the selected dielectric rods, and the light stopping can be achieved.