The nature of DNA-graphene interaction system was investigated by using molecular dynamic simulations and density functional theory calculations. The detailed adsorption behaviors of single-stranded DNA( ssDNA) and double-stranded DNA( dsDNA) on the surface of graphene were discussed. The π-π stacking would contribute to the maximum average loading of ssDNA( 167 segments) with the adsorption potential distribution at the range of-6. 0 eV to-2. 1 eV,higher than that of dsDNA( 30 segments) with the adsorption energy distribution ranging from-3. 0 eV to- 0. 2 eV. Gradually shielding the base of ssDNA using hydrogen atom and gradually changing ssDNA into dsDNA through base-pairing were performed to further detect the detailed interaction between DNA and graphene. E B for * CGC,G* GC,GC* C,and GCG* is-15. 130,-15. 276,-15. 137,and- 15. 271 eV,respectively. E B for GCGC-CGCG / graphene,GCGC-CGC / graphene,GCGC-CG / graphene,GCGC-C / graphene,and GCGC / graphene is-14. 941,-14. 700,-14. 204,-15. 561,and- 15. 810 eV,respectively. DOS of the adsorbed ssDNA down shifted 1. 885 eV,which becomes more stable and less reactive than the other cases. Further,oxidation reaction shows that graphene protects ssDNA from breaking by active oxide. And stable adsorption,protection from destroying,and undamaged desorption insure the possibility of graphene to deliver or hybrid DNA for novel and creative use. The nature of DNA-graphene interaction system was investigated by using molecular dynamic simulations and density functional theory calculations. The detailed adsorption behaviors of single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) on the surface of graphene were discussed. π-π stacking would contribute to the maximum average loading of ssDNA (167 segments) with the adsorption potential distribution at the range of -6.0 eV to-2. 1 eV, higher than that of dsDNA (30 segments) with the adsorption Gradually shielding the base of ssDNA using hydrogen atom and gradually changing ssDNA into dsDNA through base-pairing were performed to further detect the detailed interaction between DNA and graphene. EB for * CGC, G * GC, GC * C, and GCG * is-15. 130, -15. 276, -15. 137, and- 15. 271 eV, respectively. EB for GCGC-CGCG / graphene, GCGC-CGC / graphene, GCGC-CG / graphene, GCGC-C / graphene, and GCGC / graphene is-14 941, -14. 700, -14. 204 , -15. 561, and- 15. 810 eV, respectively. DOS of the adsorbed ssDNA turned down 1. 885 eV, which becomes more stable and less reactive than the other cases. Further, oxidation reaction shows that graphene protects ssDNA from breaking by active oxide. And stable adsorption, protection from destroying, and undamaged desorption insure the possibility of graphene to deliver or hybrid DNA for novel and creative use.