This invention discloses a four-layer encryption method for double grouping an encrypted authorization management system including the following steps: setting up a user ciphered key tree according to a subset difference/hierarchical subset difference unit when settin up the encrypted authorization management system to distribute pre-distributed key of users, the ciphered authorization and management system applies a four-layer of ciphered structure of double grouping to service and users to encrypt digit content in real time when distributing digit content to set up broadcasting authorization information and authorization management information to all users to be analyzed and de-ciphered by the receiving end to compute content key to decipher the digit content.