This　paper　proposes　a　security　assessment　method　based　on　rough　set　theory　for　flood　DDoS　attacks.　It　realizes　real-time　quantitative　assessment　of　security　threats.　The　hardware　structure　of　network　communication　early　warning　system　is　designed　by　taking　FTGUI-20003-1B　processor　and　warning　signal　lamp　as　an　example.　In　this　paper,　the　sensor　technology　is　introduced　to　acquire　the　state　characteristics　of　the　communication　network.　Rough　set　theory　is　introduced　to　identify　network　security　state.　It　divides　the　communication　network　link　into　the　communication　channel　composed　of　multiple　nodes　and　identifies　the　security　state　of　the　communication　network.　The　simulation　results　show　that　the　intrusion　detection　capability　of　this　method　is　strong　and　the　reliability　and　stability　of　security　detection　are　good.　©　2023　IEEE.