One triple lattice photonic crystal with a dielectric ring shape is proposed and its complete band gap is studied. By using the Rsoft software, the influence rules of each parameter on the complete band gap are studied. On this basis, the dielectric ring shaped structure is optimized. The results show that, with the increase of the dielectric constant of the dielectric ring, the complete band gap of the photonic crystal first increases and then decreases. With the increase of the ratio of inner diameter to outer diameter of the dielectric ring, the complete band gap first increases and then decreases. When the dielectric constant of the dielectric ring is 14.71 and the ratio of inner diameter to outer diameter is 0.42, the maximum complete band gap reaches 0.168.