Recent attention has been focused on the synthesis and application of flexible lithium-ion battery electrodes for the development of high-performance and durable electronic devices. Herein, we synthesize a novel composites with carbonized cotton covered by graphene/SnO2 (CGN/SnO2), in which SnO2 nano-particles grow in-situ on the cotton fibers covered with graphene oxide (CGO) under the following thermal annealing process. The conductivity of the composites and the sizes of the SnO2 particles in the composites could be expediently adjusted by changing the thermal annealing temperatures. The as-prepared flexible CGN/SnO2 composites can be directly used as an anode for lithium-ion batteries without the addition of conductive additive, binder and current collector. The CGN/SnO2 composites prepared at 500°C have exhibited a good reversible specific capacity (calculated by the weight of whole electrode) of 406mAh·g−1 (1.70mAh·cm−2) after 80cycles. This work provides an effective way for the metal oxide composed with flexible carbon framework, promising to develop a new portable electrochemical energy-storage electrode.