A novel duality and multi-level security model（DMLSM） based on intransitive noninterference theory was proposed

which protects confidentiality of information based on BLP model and integrity based on Biba model.To en-hance the usability of model

it introduces confidentiality trusted domain and integrality trusted domain which check the operations that violate the security policy in confidentiality check-room or integrity check-room respectively

then allow or refuse the access.The strict formal description of the model based on intransitive noninterference theory of informa-tion flow is given;furthermore

it proves the security of the model.The implementation of the model in Linux operating system is discussed and the application of model in practice is also demonstrated.The research gives Some contributes on the protection for sensitive important information and national information content security infrastructure.