The research and application of the diamond films were reviewed in this paper, and the nucleations on different substrates in HFCVD(I lot Filament Chemical Vapor Deposition)system were introduced. The improvement of the diamond nucleation on Si, Ni,Cu was investigated, in order to deposit diamond of high density .The P-N junction between B-implanted diamond films and N-type Si substrate was investigated. The work was shown as following:1 )The nucleation in different substrates is an important process in the deposition of diamond. By previous investigation , there are three categories of substrates. The growth of diamond on Si substrate has been extensively investigated. The density and quality of diamond nucleation on Ni substrate were great enhanced by additional CH, in the high-temperature annealing process. The Cu substrate belongs to the third category. If we deposited C60 as intermediate on the Cu substrate, using UV-light pretreatment, the nucleation of diamond was improved in fit temperature.2)The P-N heterjunction effects between B-implanted diamond films and N-type Si substrate was investigated. Polycrystalline diamond films were deposited on N-type Si substrates. In order to achieve a better distribution of the implanted element, boron ions were implanted by two steps. The I-V curves were studied , the P-N junction effect is very evident.