Along with the development of optical communication
all kinds of optic fiber in existence can not meet the requests of DWDM
but S+C+L band new single mode fiber has enough dispersion at 1 460~1 625 nm to restrain FWM and XPM nonlinear effects. At the same time
its dispersion and slope is very low that can reduce the cost of dispersion management. We designed the structure of this kind of fiber and analysed its properties.