为了更好地利用防火墙阻止拒绝服务攻击和信息泄露，针对防火墙发展现状和存在的问题基础上，提出了防火墙多级安全参考模型，设计了对防火墙的自主和强制访问控制模型；并对防火墙多级安全参考模型进行了详细分析；最后对基于多级安全参考模型的防火墙的实现作了进一步改进。关 键 词 防火墙; 自主访问控制; 强制访问控制; 参考模型; 多级安全; 拒绝服务Abstract Based on the discussion of state-of-art of firewall and its problem, discretionary access control model and mandatory access control model are designed. In order to prevent information leakage and denial of service, a multi-level reference model for firewall is proposed. The firewall reference model are analysed. The Implementation of the firewall based on the reference model is promoted in the end.Key words firewall; discretionary access control; mandatory access control; reference model; multi-level security; denial of service