As　an　emerging　technology　for　simultaneous　co-frequency　transmission,　full-duplex　technology　can　theoretically　multiply　the　spectral　efficiency,　and　with　the　improvement　of　self-interference　elimination　ability,　full-duplex　technology　shows　great　potential　in　improving　the　security　and　reliability　of　future　mobile　communication　systems.　The　broadcast　and　openness　of　wireless　channels　make　information　easy　to　eavesdrop,　and　how　ensure　the　safe　transmission　of　explosive　growth　data　has　brought　severe　challenges　to　wireless　communication　technology.　As　a　supplement　to　the　upper-layer　security　technology,　the　physical　layer　security　technology　can　be　effectively　compatible　with　the　existing　technology　and　improve　the　security　of　legal　links　from　the　perspective　of　information　theory.　This　paper　focuses　on　the　physical　layer　security　technology　of　full-duplex　trunk　systems.　©　2023　IEEE.