Abstract: Hydrogen can enhance the out-diffusion of oxygen in silicon. An annealing technology of silicon wafers at high temperature in hydrogen was studied. More than 50μm denuded zone is tested in the silicon wafers annealed at 1150℃ for at least 60min in hydrogen. The depth profile of oxygen in silicon wafers annealed was measured. It shows that there is a low oxygen content zone located in the surface layer of silicon wafers annealed. Quality of silicon wafers is improved by high temperature annealing in hydrogen. The density of oxide stacking faults is evidently reduced about one order of magnitude in silicon wafers annealed. Through high temperature annealing in hydrogen, COP defect reduces and quality of oxidation layer is also effectively improved.