Fine Zn2SnO4 nanoparticles are synthesized via a facile hydrothermal route using potassium sodium tartrate as a structure-directing agent for the first time. The average size of the as-prepared nanoparticles is about 8–10 nm. More significantly, based on the effect of the reaction time and the amounts of tartrate on the morphology evolution of the precursors, a crystal growth mechanism is proposed involving in-situ dissolution-recrystallization accompanied by morphology and phase change. The Zn2SnO4/graphene (Zn2SnO4/G) nanocomposites are further obtained through the incorporation of graphene sheets under another hydrothermal condition. When evaluated as anode for lithium ion batteries, Zn2SnO4/G nanocomposites deliver a high specific capacity of 745 mAh g−1 after 100 cycles at 200 mA g−1 and improved cyclic stability with a capacity of 492 mAh g−1 after 500 cycles at 500 mA g−1. The outstanding electrochemical performance is mainly ascribed to the synergetic effect of fine Zn2SnO4 nanoparticles and graphene nanosheets. Furthermore, our work provides a simple and low-cost synthetic strategy for the controllable fabrication of various structural materials for energy storage.