Graphene aerogels have been thought as promising adsorbents for environmental remediation, while the studies on their structure modifications and the innovation of their synthesis methods have been research hotspots in materials science. Graphene aerogel was synthesized using graphene oxide as the precursor, dopamine hydrochloride as the crosslinking agent, and L-ascorbic acid as the reducing agent by liquid phase assembly, and then methyltriethoxysilane was hydrolyzed to graft Si groups on the aerogels by chemical vapour deposition, resulting in composite graphene aerogel with silicon functional groups. The graphene aerogel was characterized by XRD, SEM and FTIR and its properties were examined. The results showed that during the formation of graphene aerogel, dopamine hydrochloride can effectively prevent the graphene sheets stack, thus making them distribute uniformly, and the graphene sheets connected each other to form a 3D porous interconnected network structure. The graphene aerogel with silicon functional groups exhibits excellent hydrophobicity and lipophilicity, and the contact angles between it and water/oil are 145.36° and 0°, respectively. Furthermore, this graphene aerogel possesses ultralow density (3.87 mg/cm3), ultrahigh adsorption capacity and unique regenerability. The adsorption capacities of this graphene aerogel toward organic solvents can reach 186.8~345.2 g/g. Moreover, it can preserve about 80% of their initial adsorption capacity even after 20 adsorption-desorption cycles.