Donaldson's continuity method of deforming cone angles for conical Kahler-Einstein metrics is an important tool in the solution of the Yau-Tian-Donaldson conjecture. We give an alternative proof to the "openness" part of this method by smooth approximation, and generalize this idea to smoothable Q-Fano variety, which allows us to prove the existence and study the deformation of singular KE metrics.