Li₂MnSiO₄ cathode material for lithium ion batteries was successfully synthesized using a high pressure hydrothermal method.The influences of pressure, reaction temperature and precursor concentration on the preparation of Li₂MnSiO₄ were carefully studied. The structure, morphology and electrochemical properties of the samples were characterized and analyzed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electrochemical test. The results show that well crystallized Li₂MnSiO₄ with high-purity material can be synthesized at high pressure. Moreover, higher precursor concentration is conducive to the formation of nanoscale particles of Li₂MnSiO₄. Electrochemical performance tests show that carbon-coated Li₂MnSiO₄/C composite has higher specific capacity than that of Li₂MnSiO₄.An initial specific discharge capacity of 178.6mAh·g^-1 can be achieved for the Li₂MnSiO₄/C cathode material at 0.1C (the current density is 33.3mA·g^-1) and a capacity retention of 97.1mAh·g^-1 after 50 cycles is 54.4%. At the same time, Li₂MnSiO₄/C also shows smaller charge transfer resistance and higher lithium ion diffusion coefficient than that of Li₂MnSiO₄.