The present invention discloses a 2D square-lattice PhC with rotated hollow square rods and rotated triangle rods comprising a high-refractive-index dielectric rod and a low-refractive-index background dielectric rod, and providing a 2D square-lattice PhC structure having a large absolute PBG relative value. The unit cell of the square-lattice PhC includes a high-refractive-index rotated hollow square rod, a high-refractive-index triangle rod and a low-refractive-index background dielectric, the hollow square rod has an outer contour being the first rotated square rod and a hollow part with a cross section being the second rotated square rod; the cross section of a high-refractive-index triangular rod is a right-angle triangle located at the hollow part of the square rod, the triangular rods are four right-angled triangular rods, the vertex connecting lines of four triangular rods form a third rotated square rod; the hypotenuse connecting lines of four triangular rods form a fourth rotated square rod.