An impact forming device and method for local small features on a metal thin-walled curved-surface part. The impact forming device includes impact forming dies, impact loading units and a forming supporting die, wherein the impact forming die is provided with an impact forming part, and the impact forming part is a convex part corresponding to a local small feature; the forming supporting die can support and fix a metal thin-walled curved-surface part without forming local small features, and the forming supporting die is provided with concave parts matched with the impact forming parts; and the impact loading unit includes a guide rail, an explosive ball and a detonating block, under the impact loading of the impact loading units, the impact forming parts can impact the metal thin-walled curved-surface part without forming local small features under the matching action of the concave parts to form the local small features.