A water quenching (WQ) method was developed to synthesize LiFePO4 and C-LiFePO4. Our results indicate that this synthesis method ensures improved electrochemical activity and small crystal grain size. The synthetic conditions were optimized using orthogonal experiments. The LiFePO4 sample prepared at the optimized condition showed a maximum discharge capacity of 149.8mAhg−1 at a C/10 rate. C-LiFePO4 with a low carbon content of 0.93% and a high discharge specific capacity of 163.8mAhg−1 has also been obtained using this method. Water quenching treatment shows outstanding improvement of the electrochemical performance of LiFePO4.