In order to better understand the bonding mechanisms of the phosphorus-doped diamond films and the influences of the phosphorus-doped concentration on the diamond lattice integrity and conductivity, we calculate the electronic structures of the phosphorus-doped diamond with different phosphorus concentrations and the density of states in the phosphorus--doped diamond films with a vacant lattice site by the first principle method. The calculation results show the phosphorus atom only affects the bonds of a few atoms in its vicinity, and the conductivity increases as the doped concentration increases. Also in the diamond lattice with a total number of 64 atoms and introducing a vacancy into the non-nearest neighbor lattice site of a phosphorus atom, we have found that both the injuries of the phosphorus-doped diamond films and the N-type electron conductivity of diamond films could be improved. phosphorus-doped, impurity level, vacancy, diamond lattice PACS: 71.15.Mb, 71.20.-b, 81.05.ug, 68.55.agDiamond, an allotrope of carbon, has many excellent characteristics, such as extremely high degree of hardness and wear-resisting performance, high breakdown voltage and electron-hole mobility, excellently thermal conductivity and biological compatibility, low dielectric coefficient and good chemical inertness. These characteristics fit a wide range of potential applications in the mechanics, heat, electrics, magnetic, optics and other fields. The diamond semiconductor devices can be used in the adverse circumstances of high temperature, high pressure and strong radiation and other harsh environments. Diamond has an extremely attractive prospect in the semiconductor industries and microelectronic fields. Because the PN junction is the basic structure of the semiconductor electronic devices, it needs to be prepared with the P-type diamond and the N-type diamond. The present technology of the P-doped diamond thin films (mainly boron-doped films) has become quite mature and is fully used in the treatment of the environment [1-4], medicine [5,6] and industries [7][8][9]. However the preparations of the N-doped diamond thin films are quite difficult, the impurity levels of the N-diamond films are relatively deep, and the electrical resistivity is very high. The N-doped diamond thin films can't meet the technical requirements of the semiconductor electronic devices. Thus these difficulties limit the application of the N-doped diamond thin films in the electronics fields.With microelectronic industries rapidly developing, the research of the N-type diamond has attracted more and more electronic industries' technicians and researchers. The impure atoms of the N-type diamond mainly contain lithium, sodium, nitrogen, phosphorus, oxygen, and sulfur. Li and Na are always interstitial atoms, while nitrogen, phosphorus and other atoms are the substitution atoms. In 1990, the photoemission properties of lithium-doped diamond thin