The present application provides a method for preparing a p-type semiconductor structure, an enhancement mode device and a method for manufacturing the same. The method for preparing a p-type semiconductor structure includes: preparing a p-type semiconductor layer; preparing a protective layer on the p-type semiconductor layer, in which the protective layer is made of AlN or AlGaN; and annealing the p-type semiconductor layer under protection of the protective layer, and at least one of the p-type semiconductor layer and the protective layer is formed by in-situ growth. In this way, the protective layer can protect the p-type semiconductor layer from volatilization and to form high-quality surface morphology in the subsequent high-temperature annealing treatment of the p-type semiconductor layer.