With the rapid development and wide application of computer network, it is new challenge to information security and network security. Traditional security models and single security technology cannot keep up with the change of complicated network structure and varied intrusion measure. Network security manage based on policy has traits of low manage cost, high agility, wide applicability. Mobile agent not only collects but also process data, overcomes traditional agent's shortcomings, improves response and relieve network burden. This paper introduces network security management based on policy and mobile agent into new network security framework, and emphases on its structure, control strategy and implementation.