The nanosized-precipitate behavior of ferritic 11Cr heat-resistance steel subjected to high temperature creep damage was investigated. The ferritic 11Cr4W3Co steel has been prepared by vacuum induction melting process. The microstructure shows significant changes in precipitate size and precipitate number. With increasing aging time, the size of the precipitates clearly grew following the Ostwald ripening. The coarsening rate of Laves (Fe₂W) phase is much faster than that of other precipitates such as Cr23C6 and NbC carbides.