In this work, SnO2 quantum dots and graphene (G) nanocomposites (SnO2/G) were synthesized via a facile one-step hydrothermal method for the application of anode material in lithium ion batteries (LIBs). SnO2 quantum dots with a diameter ranging from 5 to 10nm were uniformly anchored on graphene nanosheets. SnO2/G nanocomposites can deliver high specific capacities of 860mAhg−1 after 50 cycles at a current density of 200mAg−1, and 683mAhg−1 at a current density of 1600mAg−1. Compared to the pure SnO2, the excellent improved electrochemical performance of SnO2/G nanocomposites for lithium ion storage can be attributed to the stable structure and the improved electron conduction channel provided by graphene with functional groups (FGs), such as C-OH, C=O and C-OOH. In order to further improve the SnO2/G nancomposites electrochemical performance, carbon thin layers were coated by the reduction of C2H2 gas via CVD technology (SnO2/G-C). However, SnO2/G-C showed an inferior performance compared to that of the SnO2/G without carbon coating. Through X-ray photoelectron spectroscopy (XPS) analysis, it was found that function groups play a critical role on the stability of SnO2/G nanocomposites. Such observation may thus instruct the design and implementation of graphene/metal oxides nanocomposites for high-performance LIBs anode materials.