Abstract: To study the effect of fiber core structure on properties of hollow-core photonic crystal fibers ( HC-PCFs), 7-cell HC-PCFs with two types of fiber core shape were designed and compared to the traditional dodecagon HC-PCFs. The finite element method ( FEM) was adopted to simulate them. The results show that the concave round type has lower leakage loss and waveguide dispersion than that of dodecagon type, and concave rectilinear type has a special waveguide dispersion characteristic, the new designs of the fiber core structure can be used for large capacity optical communication, optical soliton transmission and dispersion compensation in the future.