In this study, the electrochemical characteristics of porous silicon/carbon composite anode were investigated to improve the cycle stability and rate performance in lithium ion batteries. In this study, the effect of TEOS and NH3 concentration, mixing speed and temperature on particle size of nano silica was investigated using Stober method. Nano porous Si/C composites were prepared by the fabrication processes including the synthesis of nano SiO2, magnesiothermic reduction of nano SiO2 to obtain nano porous Si by HCl etching, and carbonization of phenolic resin. Also the electrochemical performances of nano porous Si/C composites as the anode were performed by constant current charge/discharge test, cyclic voltammetry and impedance tests in the electrolyte of LiPF6 dissolved inorganic solvents (EC:DMC:EMC=1:1:1vol%). It is found that the coin cell using nano porous Si/C composite has the capacity of 2,006 mAh/g and the capacity retention ratio was 55.4% after 40 cycle.