Li2FeSiO4 nanoparticles are successfully synthesized via hydrothermal approach, with the hydrothermal process monitored in detail. Structural characterizations by XRD, FTIR, SEM and HRTEM measurements reveal that the Li2FeSiO4 nanoparticles have a high crystalline degree and monodisperse nanoparticle shape with a size around of 50–200nm. To further improve the electronic conductivity, the Li2FeSiO4 nanoparticles are coated by a carbon layer using in suit polymerization of dopamine. Moreover, the effect of carbon content for electrochemical performance of Li2FeSiO4/C is systemically investigated, and as a result, the composite with a ratio of Li2FeSiO4 and dopamine of 3:1 demonstrate the best electrochemical performance with a discharge specific capacity of 148mAhg−1 at a rate of 0.1C at room temperature. Furthermore, the electrochemical performance of Li2FeSiO4/C at high temperature of 55°C is also investigated, and it also exhibits a good performance with a discharge specific capacity of 240mAhg−1at a current rate of 0.2C.