A novel structure of photonic crystal fiber (PCF) is proposed ,and the dispersion and nonlinear properties of the PCF are analyzed numerically based on full vector finite element method. Three PCFs with high linearity and nearly-zero flattened dispersion or broadband flattened even ultra-flattened dispersion in different wave bands are obtained by optimizing the structure parameters, and the method is presented to fabricate the microstructured fiber preform as well. These novel PCFs proposed have bright prospects of applications in all-optical format conversion, super-continuum generation and optical wavelength conversion，and other fields.