Using improved fully vectorial effective index method(IFVEID),while keeping the structure parameters altered,the dispersion coefficient,the effective mode area and the nonlinear coefficient of PCF as a function of wavelength is investigated.Based on the analysis,a highly nonlinear PCF with low flattened dispersion on the verge of infrared wave band nearby 900nm is designed by ourselves.Furthermore,it is fabricated with the extrusion method of the cladding holes infused air through improving the technics.Although the PCF fabricated has not achieved the ideal value,its dispersion coefficient is merely 0.75 ps/km/nm and non-linear coefficient achieves 30 (W/km)-1,higher in PCFs made of silicon.