The dispersion properties of photonic crystal fibers(PCFs) with hybrid cores were systematically investigated by using plane-wave expansion method. The numerical calculation results show that an ultraflattened dispersion range of more than 800 nm in which the variation of dispersion is less than 0.6 ps·km^－1·nm^－1 can be achieved at～1.55 μm by properly designing the structure parameters of the PCFs.