A finite difference scheme based on semi-vectorial wave equations is used to study the dispersion properties of photonic crystal fibers (PCF). Using a central difference scheme, the semi-vectorial wave equations are cast into algebraic eigenvalue problems, from which modal fields and propagation constants are obtained. The results obtained by the semi-vectorial finite difference method are coincided well with those by the full-vectorial finite difference method and the finite element method as well as experimental results, and are more accurate than those by the scalar effective index model. It can be shown that the semi-vectorial finite difference method is an effective numerical tool for the design of photonic crystal fibers with desirable dispersion.