Nano porous materials LiFe0.75Mn0.25PO4/C were prepared by sol-gel method. The influences of sintering temperature on particle size, pore size distribution and cycling performance were studied. The results show that ratio of the mesopore in diameter 9.5 nm increases gradually with the increase of sintering temperature. The material sintered at 750 °C has high crystallinity, the particle size under 100 nm, the specific surface area of 80.3m2 g−1, about 3 nm carbon coating, and higher ratio of the mesopore in diameter 9.5 nm. These are beneficial to the diffusion of lithium ion and the transfer of electrons, and high electrochemical performance material has been obtained. The initial discharge specific capacity is 120.28 mAhg−1, it remains 80.71mAhg−1 at 10C after 600 cycles.