The invention discloses a structural data asset leakage prevention method based on hierarchical classification. The method comprises the steps: a, a user client side sends a structural data access request to a database server by an application server; b, a database protection server analyzes an SQL (Structured Query Language) statement by the flow of a mirror image, and judges whether the access request contains an illegal access; c, if the access request does not contain the illegal access, access request data are returned. A structural data leakage prevention method based on ciphertext is utilized, so that sensitive structural data in enterprise information assets are effectively prevented from being leaked; in addition, the structural data leakage prevention method based on ciphertext is utilized, high sensitive data, sensitive data and internal data are encrypted in advance, during access, only security classification of a user and a security classification value allowing the user to access both meet the requirement, corresponding data lines can be deciphered and accessed, and thus the safety of the high sensitive data, the sensitive data and the internal data is further effectively protected.