A novel broadband polarization beam splitter (PBS) based on dual-core photonic crystal fiber is proposed. With a full-vector finite element method, the effects of structural parameters of fiber on the bandwidth and length of PBS are systematically investigated in detail. Numerical results indicate that an increase in the index of fluorine-doped region can not only broaden the bandwidth but also shorten the length of PBS. An increase in the diameters of air hole and hole pitch in an optical fiber can broaden the bandwidth of PBS, however, lengthen the length of PBS at the same time. Thus, it is necessary to balance the bandwidth and length of PBS when selecting the fiber structure parameters. Through optimizing the fiber structure parameters mentioned above, a kind of ultra-broadband PBS is achieved. When the extinction ratio is greater than 20 dB, the length of PBS is as short as 7.362 mm and its bandwidth is more than 600 nm.