The notion of restricted Lie algebras has played an important role in the modular Lie algebra theory， especially in the classification of the simple modular Lie algebras. It is necessary to develop restrictedness theory for the classification of the simple modular Lie superalgebras. In this paper，the restrictable Lie superalgebras，the restricted envelopes and universal restricted-envelope are studied. A restrictable Lie superalgebras is proved to be restricted Lie superalgebras. The structures and some properties of the restricted envelopes and universal p-envelope are obtained.