The proposed BLP-i is based on the classical Bell-LaPadula model, and it redefines new object datatype, object hierarchical structure, referential relation, etc. These make integrity properties become inherent properties of the model. The model uses the view function to expresses the axiom and the rules of operation.To reduce the need of trusted codes and prevent covert channels,the model restricts that transactions in system are single-level and restricts object's some behaviors. By those ways, the proposed mode can preserve data integrity defined in the model while it's multilevel secure.