The heterogeneous extended diamond films have been deposited on(100) silicon in O2/H2/CH4 mixture atmosphere by microwave plasma chemical vapor deposition(MPCVD)method.We characterize the structure and morphology of diamond films by X-ray diffraction(XRD),Raman spectrometer and field emission scanning electron microscopy(FESEM).The results show that the prepared diamond films have high diamond phase purity and closely arranged grains.AlN thin films with highly C-axis preferential orientation are deposited on polished diamond substrates by RF magnetron sputtering.The influence of sputtering pressure and target-substrate distance on the AlN film preparation has been studied.X-ray diffraction(XRD) tests show that the AlN(002) preferential orientation easily forms at low sputtering pressure and short target-substrate distance,while it is more favorible to the AlN thin films with preferential orientations(103) and(102) under contrary conditions.The growth mechanisms of AlN thin films on different surfaces of diamond substrate are studied.It is found that AlN thin films deposited on nitrogen-terminated diamond substates have AlN(002) preferential oritentation.The influence of the formation of Al-N chemical bond and the mean free path of sputtering particles on the preferential orientation of AlN thin films is also discussed.