The guiding problem in microstructure fiber with 780 nm zero dispersion wavelength is accurately analyzed through a reduced vector wave equation, using a novel finite element method (FEM). The two-dimensional transverse intensity distribution of the fundamental mode, the effective refractive index, dispersion curves of guided modes for different fiber structural parameters are calculated. The results match those achieved in recent experiments in which the feasibility of this type of fiber was shown. Furthermore, this method is used for simulating the random distributed microstructure fiber, and a reasonable result is gotten rapidly and accurately.