Since 2Dphotonic crystal has been successfullyfabri-cated[1], many researches have shownthat loweringthesymmetry of the photonic crystals can contribute to ob-taining a large Photonic band gap(PBG)[2]. More re-cently,it has been shown that reorienting the directionof square rods in square lattices can make an absolutePBG appear and even move towards the direction ofhigher frequency[2]. In this letter we mainly concerned with the absolutePBGin 2D square lattice structures , which array with…