A facile method was developed to synthesize B-doped carbon coated nano-sized Li4Ti5O12 by using glucose and boric acid mixture as the precursor of coating layer, and the effect of B-dopant amounts on electrochemical performance was investigated in detail. It is demonstrated that B-dopant can efficiently improve the electronic conductivity of carbon-coating layer. According to X-ray photoemission spectroscopy analysis and electrochemical investigation, it is also found that, BC3 dopant species are important for improving electronic conductivity and electrochemical performance, whereas the B-O dopant species, which increases with the enhancement of B-dopant amount, might hamper the charge transfer on Li+-insertion process. Therefore, the carbon coated nano-sized Li4Ti5O12 with a moderate B-dopant amount exhibits much higher electrochemical performance. For example, with a low carbon content of ∼3wt. %, the optimized B-doped carbon coated Li4Ti5O12 can deliver a capacity of around 90mAhg−1 at a high rate of 20C, which is much higher than that of carbon-coated Li4Ti5O12. The achieved result indicates that approach of B-doped carbon coating is an effective method for improving the performance of Li4Ti5O12.