The composite materials of B-doped LiFeP1−x B x O4−δ /C (x = 0.00, 0.05, 0.10 and 0.15) at P-site are synthesized in flowing N2 atmosphere by liquid phase reduction method with heat treatment. The synthesized products are characterized by X-ray diffraction, SEM, cyclic voltammetry and galvanostatic charge/discharge tests. The results show that the samples all have well-regulated olivine-type structures, high crystallinity, moderate and uniform particle size, while B-doping improves the conductivity of composite materials, decreases the polarization of electrode, and enhances the cycling performance and high rate capability effectively. The LiFeP0.9B0.1O4−δ /C composite exhibits the best electrochemical performance in the all samples. The discharge capacities of LiFeP0.9B0.1O4−δ /C are 155.2 mAh g−1, 146.2 mAh g−1, 139.4 mAh g−1, 132.4 mAh g−1, 119.1 mAh g−1 and 102.6 mAh g−1 at the rate of 0.2C, 0.5C, 1.0C, 2.0C, 5.0C, and 10.0C.