The shifts of zero dispersion wavelength for a few of impure fiber due to the Change of refractive index of fiber have been researched. A numerical analysis method used for calculating phase matching with the parametric effect is put forward, the phase mismatching from the material and waveguide dispersion of the fiber in the parametric effect is calculated by the numeric method and the spatial curvature surfaces of phase mismatching Changed with both pump light wavelength and frequency shift between the pump and signal light are given. The results show that there is the biggest flequency shift meeting the condition of the phase matching near the zero dispersion position and this rule doesn't changed with the shift of zero dispersion.