SnOx attracts considerable attention as an anode of lithium‐ion batteries (LIBs) because of its high theoretical capacity. However, SnOx suffers from poor cyclability and rate capability caused by large volume change upon cycling and low conductivity, which severely limits its application for LIBs. Herein, a nanocomposite of Sn/SnO2/C is synthesized for the first time under an elevated pressure originated from the pyrolysis of dimethyltin oxide in a sealed vessel. The Sn/SnO2/C nanocomposite consists of a homogeneous dispersion of Sn and SnO2 nanocrystals (<10 nm) into the carbon matrix, which endows it with an enhanced lithium storage performance. The Sn/SnO2/C nanocomposite delivers an excellent cyclability (0.025% capacity loss per cycle during 1000 cycles at 1 A g−1) with an improved rate performance (243.8 mAh g−1 at 5 A g−1).