Photonic crystal fibers（PCFs）with rectangle core and elliptical core have been designed.Their fundamental characteristics are studied by electromagnetic scattering theory of multipole method.It is found that the fiber birefringence,dispersion and nonlinear characteristics can be flexibly adjusted by changing the radius of the air holes in the core.The PCFs have the following characteristics: With the increase of radius r1 of air holes in the core,the birefringence increases and the wavelength corresponding to the maximum birefringence shifts towards the longer wavelength region,the number of zero-dispersion-wavelengths increases from one to three and nonlinear coefficient of the short-wave band decreases while it increases in the longer wavelength region.The three zero-dispersion-wavelengths of elliptical core PCFs with r1 = 0.4 μm are located in visible,near-infrared and mid-infrared band,respectively.For similar structural parameters,elliptical core PCFs can achieve high birefringence and high nonlinearity more readily than rectangular core PCFs.