Novel highly nonlinear photonic crystal fibers (HN-PCFs) with flattened dispersion are proposed by omitting 19 air holes as the fiber core. The simulation results show that the high nonlinearity and the flattened dispersion can be achieved simultaneously by employing only two types of air holes in the cladding. To reduce the confinement loss, the modified designs are presented. The confinement loss is below 0.1 dB/km at 1.55 μm, when seven layers of air-hole rings are introduced to the cladding. After modifying, the dispersion can change from −0.5 ps/(nm·km) to +0.5 ps/(nm·km) in the range from 1.35 μm to 2.06 μm, and the effective mode area is as low as 2.27 μm² at 1.55 μm.