Abstract: A rapid and continuous method for synthesis of LiFePO₄ nanoparticles in supercritical water was established.The effects of reactant concentration，temperature，and pressure etc. on size，crystallinity degree，and morphology of LiFePO₄ particles were investigated and possible reasons for this behavior were also given.The crystallinity degree，size，and morphology of objective product were characterized by SEM，DLS，and XRD．Results showed，nano-sized LiFePO₄ were obtained in all the researched parameter ranges.In the supercritical range，with the reaction temperature increased，the particle size became bigger，but distribution more uniform；the pre-heating temperature had a significant impact on crystallinity degree and higher pre-heating temperatures were found to be in favor of improving the crystallinity degree of LiFePO₄ nanoparticles; higher pressure and lower reactant concentration could get smaller nanoparticles；and olivine-like spherical LiFePO₄ nanoparticles with average size of 105 nm and high crystallinity degree were obtained under the conditions of reaction temperature of 380 ℃，pre-heating temperature of 405 ℃，reaction pressure of 27 MPa，and Fe²⁺ concentration of 0.015 mol/L.

Key words: continuous synthesis, LiFePO₄, nanoparticle, supercritical water