Based on the plane wave expansion method of numerical simulation of triangular lattice photonic crystal band gap properties,dielectric constant of 8. 9 and 8. 9 when the band gap center,the band gap rate and the characteristics of band gap width change with radius,with the increase of the radius band gap center frequency also gradually increase,rate of band gap,band gap width increases after the first decreases,and the results of the study has reference value for the design of photonic crystal.