The invention relates to a two-dimensional photonic-crystal optical router based on a nested ring cavity structure. A two-dimensional photonic crystal, which is a triangular lattice medium column structure, is formed by one ring cavity including one large non-equilateral hexagon and one small non-equilateral hexagon which are nested, wherein the ring-shaped cavity is guided in two horizontal input and output waveguides. Several medium columns are distributed in the ring cavity in a central symmetry mode, and the whole structure is distributed symmetrically. An appropriate structure parameter is selected. The router can simultaneously realize forward bottom route and backward bottom route functions of a single wavelength input light wave, the forward bottom route and backward bottom route functions of two wavelength input light waves, and a function of exchanging forward and backward bottom route directions of two wavelengths. Compared to the two-dimensional photonic-crystal optical router of a single ring cavity structure, by using the router of the invention, a bottom route effect is obviously increased and can reach 100%. The router possesses characteristics that the structure is simple; manufacturing is easy; a size is small; cost is low; stability is high; and flexible functions are possessed and so on. The router can be mainly applied to an all-optical integrated loop network.