IntroductIon Graphene as new material, due to its unique and novel properties has attracted extensive attention and in-depth research in the scientific community. Graphene, as a covalently bonded monolayer of carbon atoms with a hexagonal structure, is currently the thinnest material found in the world, and also makes it one of the world's best in terms of its properties [1] . Graphene, with this special structure, contains rich and novel physical phenomena, which make it show many excellent

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... perties such as ultra-higqh carrier mobility, good thermal conductivity, excellent mechanical modulus (1 TPa), breaking strength (125 GPa), and also a superior gas barrier, high transparency, and high specific surface area [2] . Moreover, based on these extraordinary properties, graphene showed great potential application prospects and market value in different fields such as transportation, high-frequency electronic devices, flexible display, electrochemical biosensor, new energy battery, supercapacitor, aerospace, biomedical, etc. Graphene can also be used as an ideal nanofiller to reinforce the properties of composites, thus providing a broader application space for composite materials. Even a small amount of graphene addition to composite tends to increase the mechanical, electrical, and processing properties [1] [2] [3] [4] . Hence, the addition of graphene into polymer composite has shown improvements of properties compared to pure polymer, significant changes in the mechanical, electrical, and thermal properties were proven, more than in the case of other materials. The polymer nanocomposites modified by graphene can be used in construction, automobile, aerospace, electronic, and medical applications, etc. The interaction between fillers and the polymer matrix at the interface has great importance for the performance of composites [5, 6] . As graphene is hard and very costly to produce, needs a lot of energy, and is difficult to control structure, coupled with other materials especially polymers, different alternatives were found by using modified graphene, such as graphene oxide (GO) and reduced graphene oxide (RGO) (Fig. 1) , etc. provided more options which are considered easy to produce and showed a great improvement when combined with polymers. Generally, modified graphene (GO, RGO, etc) coupled with polymers and polymer composites can be possibly reached easily using various AbstrAct Graphene has shown unique properties and introduced new challenges to light materials applicable in different areas. In addition to the polymer, it has brought materials with marvelous properties: mechanical, electrical, thermal, and related to conductivity. Different methods were discovered to produce good nanocomposites. This review summarized those methods, as well as discussed the properties of graphene combined with different kinds of polymers. Furthermore, the different factors affecting graphene reinforced polymer nanocomposites were studied. In the end, the challenges and future prospects for graphene polymer nanocomposites were considered.