Abstract: The coarsening kinetics of γ' precipitates in GH169 alloy have been studied with transmission electron microscope. The measured coarsening rates and particlesize distributions were analyzed using LSW theory. The results show that the growth behavior of γ' phase follows the time-law predictions of LSW theory of diffusioncontrolled growth. However, the actual particle-size distribution is anomalous, it could be attributed to the γ' phase special characteristic of high density dispersion precipitation and a large lattice misfit.