Graphite, with a theoretical storage capacity of Li ions with an equivalent of 372 mAh/g, has been used as anode in commercial lithium ion battery for decades. Due to the advancement of electronic portable devices and the development of electrical vehicles, higher capacity and energy density anode materials are needed. Silicon, which has a theoretical capacity 3579 mAh/g, has been explored as the next generation anode material. Being different from graphite, Li has an alloying reaction with Si instead of intercalation, which leads to severe volume expansion (as much as 370%) during charging.  The repeated volume change during cycling can destroy Si particles and the surrounding solid electrolyte interphase and leads to capacity fade. Reducing the size of Si particles has been proven as an effective way to alleviate decomposition. Therefore, Si has been synthesized as thin film, nanowires, and nanoparticles to improve its cycling stability. For nanosized Si, the capacity retention is satisfying even with high amounts of Si contained in the electrode. In this work, nitrogen doping of silicon is used to further improve the cycling performance of the Si nanoparticles. It is found that N-doping modifies the crystallization of Si nanoparticles leading to amorphous Si nanoparticles with high nitrogen concentration. At the same time, with increasing N doping concentrations, the specific capacity decreases. However, better capacity retention, rate performance, and reduced side reactions can be achieved. It is demonstrated that high-performance Si-based anode material can be obtained by carefully controlling doping nitrogen in Si nanoparticles.