The effect of stuffing rate on band gap structure of finite height 2-D photonic crystals was investigated.Two kinds of crystal lattices are considered:the triangular lattice with air hole and square lattice with dielectric rod.The 3-D plane wave method is used to calculate the eigen equation.The characteristics of the band gap structure are analyzed.The results shows that while the air included in a unit cell increases,the band gap tends to be in a higher frequency zone and also become wider,and the width of the band gap is also restricted by the light cone.While the dielectric constants are 2 and 12,total height is 3L_1,the heights of the middle layer for triangular and square lattice are L_1=0.6 a and L_1=1.5 a respectively,large band gap can be found at r/a=0.42 for triangular lattice and r/a=0.19 for square lattice.