The thermal stability of oxygen precipitates formed by prolonged annealing at 1000℃ in conventional Czochralski silicon and nitrogen-doped Czochralski silicon has been comparatively investigated. It was found that a majority of the existing oxygen precipitates in the nitrogen-doped silicon were dissolved by both conventional furnace annealing and rapid thermal annealing at 1200℃, while those in the conventional Czochralski silicon dissolved at 1250℃, as a result of nitrogen enhancing denser oxygen precipitates with smaller size. Furthermore, it can be considered that the dissolution of oxygen precipitates is primarily determined by the annealing temperature.