Carboxymethyl chitosan (C-CTS) was firstly reported as a water soluble binder for LiFePO4 cathode in Li-ion batteries. The electrochemical performances of LiFePO4 cathode with C-CTS binder was investigated and compared with the conventional water-soluble sodium carboxymethyl cellulose (CMC) and the commercial non-aqueous polyvinylidene difluoride (PVDF). LiFePO4 cathode with C-CTS exhibited a comparable cycling performance, but better rate capability than that of CMC and PVDF, retaining 65% capacity of C/5 at 5C rate as compared with 55.9% and 39.4% for CMC and PVDF, respectively. In addition, LiFePO4 cathode with C-CTS exhibited excellent cycling performance at 60°C, retaining 91.8%/62.1% capacity after 80 cycles at 1C/10C, respectively.