A dispersion-compensating square-lattice photonic crystal fiber for broadband compensation which covers the S,C and L communication bands,i.e.wavelength ranging from 1 460 nm to 1 625 nm is proposed in this paper.Theoretically,it is shown a negative dispersion coefficient of about-595 ps/(nm·km)to-1 288 ps/(nm·km)over S to L bands and-975 ps/(nm·km)at the operating wavelength 1 550 nm.The relative dispersion slope is perfectly matched to that of conventional single-mode fiber of about 0.003 6 nm-1.Besides the proposed photonic crystal fiber shows the large non-linear coefficient of 61.88 W/km at the operating wavelength of 1 550 nm.Moreover,the variation of structural pa-rameters is also studied and discussed here.