We have systematically investigated the morphological evolution of Ge0.5Si0.5 strained films during postdeposition annealing. The changes of the surface structure are found to follow the kinetic route of strain relaxation at different stages. A number of interesting features are revealed, which include the existence of an energy barrier to the two-dimensional/three-dimensional (2D/3D) transition, and a self-limiting effect in the growth kinetics of strained 3D islands. We demonstrate that the annealing approach provides a new way to grow coherent islands with uniform size.