As Li-ion batteries (LIBs) anode material, SnO2 has a high theoretical capacity while it faces the challenge of poor cycling performance. To solve this problem, conductive SnO2/C nanocomposites were prepared in this work by a novel, one-step method. Through annealing the tin (IV) acetate at 550 °C, the obtained SnO2/C nanocomposites with small particle size (lower than 20 nm) possessed the virtues of carbon-based materials. Since small particle size could shorten the Li ion transmission path and carbon materials could improve the electrical conductivity as well as relive the volume expansion, the SnO2/C nanocomposites exhibited superior cycling performance which kept at 464 mAh g−1 at the current density of 500 mA g−1 after 75 cycles. The experimental results indicated that the SnO2/C nanocomposites also displayed excellent rate performance. Therefore, the facile method for preparing SnO2/C nanocomposites will provide a novel strategy to improve the electrochemical performance of SnO2 in LIBs.