The dispersion characteristics of photonic crystal fibers are computed using the multipole method. Single-mode fiber with three zero-dispersion wavelengths is obtained by properly designing fiber structure parameters. The dispersion characteristics of photonic crystal fiber with a small air hole in the core are analyzed. Fibers with four zero-dispersion wavelengths are designed. The variation rules of zero-dispersion wavelength with fiber structure parameter are found. The locations and spacings of the zero-dispersion wavelengths can be adjusted flexibly in a large wavelength range. Closing to zero and flattened dispersion can be obtained in the fibers with multiple zero-dispersion wavelengths. The multiple zero-dispersion wavelengths can create a rich phase-matching topology, and enable better controlling the spectral locations of the four-wave-mixing and resonant-radiation bands emitted by solitons and short pulses.