The order-N method is used to study the transmission properties of heterostructures of two-dimensional (2D) photonic crystal. Three different heterostructures, i.e., refractive index, pole′s shape and lattice structure heterostructures are numerically calculated respectively. Numerical results show the property of single direction guidance of light, which is similar to that of the semiconductors of electronic type. Analogous analyzing between these two phenomena was made with a simple theory. It is further shown that guide modes appear not only in the case of lattice structure aberrance but also in the other two cases.