The invention discloses a method and a system for preventing sensitive data leakage. The method comprises the following steps: establishing an original sensitive field library by utilizing a preset sensitive field discovery algorithm; obtaining metadata in the whole life cycle process of the sensitive data; according to the original sensitive field library and the metadata, analyzing a model and acode in a sensitive data circulation process, and obtaining a blood relationship and a use path of sensitive data in a full link; obtaining a sensitive data use list by utilizing the blood relationship and the use path of the sensitive data; analyzing the sensitive data conversion process by using a preset data feature analysis algorithm to obtain a sensitive data check list; performing early warning and auditing sensitive data. According to the method, the original sensitive field library, metadata management, model and code analysis, sensitive data blood relationship, sensitive data contentfeature analysis and early warning audit are combined, so that the transfer and use process of the sensitive data is more intuitive and clearer, and the risk of sensitive data leakage in each link inthe full life cycle of the data is effectively reduced.