Graphene-wrapped poly 2,5-dihydroxy-1,4-benzoquinone-3,6-methylene (PDBM) nanocomposites with three-dimensional nanoflower structures have been successfully prepared through the ultrasonic exfoliation and reassembly process in methanol. Compact distribution of graphene into the nanocomposite has established a three-dimensional conductive network, which contributes to improved properties on discharge capacity and cycle performance. Composite with 20 wt% graphene was proved the best ratio when used in sodium-ion batteries. Its initial discharge capacity can achieve 210 at 30 mA g(-1). After 100 cycles, the capacity is stable at 121 mAh g(-1). The composite featuring highly conductive channels and multidimensional electron transport pathway is synthesized by an easy ultrasonic way, which may be applied in large scales for sodium-ion batteries.