The surface structure, electronic properties, lattice dynamics, and the electron-phonon coupling for p-doped diamond (001)-(2 x 1) and (111)-(2 x 1) thin films have been extensively investigated using ab initio methods within the virtual crystal approximation. The calculations of p-doped diamond thin films strongly favor dimer reconstruction of diamond surfaces. The physical origin of superconductivity of diamond (001)-(2 x 1), respectively, and (111)-(2 x 1) thin films which is higher than that of bulk diamond is systematically studied. It is showed that surface vibrational modes of diamond (001)-(2 x 1) surfaces give main contributions to superconducting transition temperature T(c), while T(c) of diamond (111)-(2 x 1) surfaces is attributed to the combined action of surface and bulk vibrational modes. Therefore, at the highest concentration (13.98 x 10(21) cm(-3)) T(c)approximate to 56.5 K of diamond (111)-(2 x 1) surfaces is about twice as high as that of bulk and diamond (001)-(2 x 1) surfaces. (C) 2010 Elsevier B.V. All rights reserved.