Graphene attracts lots of research attentions for versatile properties. Due to the limitation of experimental technologies, various theoretical studies of the real nanomaterials were carried out. Many fundamental quantum mechanics studies could illustrate the band structure of graphene, which has great relationships with its macroproperties. In order to broaden the application of graphene, various studies about the interactions between gases molecules and graphene has been done. It is indicated that graphene can be good gas sensors by metallic doping modifications. Metallic doped graphene also exhibits potential applications in hydrogen storage. Meanwhile, our pervious study of interactions between chitosan and graphene indicates that the interfacial interactions between graphene and chitosan could be regulated by the functional groups modification of graphene. Many other studies could be done to exploring the potential applications of graphene by theoretical methods. These would be very meaningful for the understanding and practical application of the nanomaterials.