A microstructured fiber (MF) with closing-zero flattened dispersion is proposed. The effect of air hole diameter and hole-pitch on dispersion of fiber is analyzed by the finite element method(FEM). By optimizing the air hole diameter and hole-pitch, closing-zero flattened dispersion and large mode area can be realized in a very wide scope of wavelength. When the air hole diameter d=0.73 μm and the air hole-pitch Λ=2.2 μm, the wavelength is from 1.22 μm to 1.80 μm, the dispersion parameter is only within ±1 ps/(nm·km) in a 600 nm wavelength range, and three zero dispersion wavelength with 1.26, 1.51 and 1.76 μm can be achieved. When d=0.73 μm, Λ=2.3 μm, and the wavelength is from 1.20 μm to 1.65 μm, the dispersion parameter is within -2～4 ps/(nm·km) in a 400 nm wavelength range, and one zero dispersion wavelength with 1.24 μm can be achieved.