This paper proposes a compound triangular lattice-based infrared photonic crystal fiber.This fiber uses chalcogenide glass Ge30Sb8Se62 with good transmittance as the substrate material.The lattice consists of circular and square dielectric cylinders

which are horizontally and vertically dislocated in an interphase nested arrangement and every two adjacent cylinders are inclined to each other at 60°.This paper analyzes the photonic bandgap and limit loss characteristics of the fiber in different structures by using the plane wave expansion method and the finite element method and obtains a large bandgap and low-loss photonic crystal fiber at 10.6μm by optimizing the structural parameters of the fiber.