American literary theorist Said gave a new interpretation of the concept of"boundary"from the perspective of ideological concepts.Based on the power composition model of the"local authority central authority"of postcolonial cultural hegemony,he revealed the identity function of"boundary"in distinguishing between"self"and"other"issues;The British Tanzanian writer Abdulrazak Gurnah and his short story Cages revolve closely around the issue of identity.Through deeply portrayed novel characters and carefully arranged story scenes,they creatively reveal new features of"internalization"and"diversification"in the division of"boundaries"and get a new exploration of the internal flow process of colonial discourse.