In　order　to　study　the　method　of　strengthening　earthquake-damaged　precast　concrete　(PC)　frame　structure,　the　quasi-static　pre-damaged　test　of　PC　structure　interior　joints　of　two　full-scale　plane　workbenches　was　completed.It　is　found　that　horizontal　and　vertical　shear　cracks　occur　along　the　joint　surface　between　the　precast　beam-column　and　the　core　area　of　the　joint.According　to　the　failure　mode　of　the　PC　joint,　a　method　of　strengthening　earthquake-damaged　PC　joint　with　externally　bonded　carbon　fibre　reinforced　plastics　(CFRP)　and　beam-end　haunch　was　proposed.The　result　of　quasi-static　test　on　strengthening　earthquake-damaged　PC　joints　indicates　that　the　plastic　hinge　region　of　the　beam　end　moves　from　the　region　neared　the　joint　core　area　to　the　end　of　the　beam　haunch,　and　the　joint　surface　of　the　beam-column　and　the　joint　core　area　are　not　cracked.After　earthquake-damaged　joints　are　reinforced,　the　cumulative　energy　consumption　of　the　GJ-1　and　GJ-2　joints　increases　88.1%　and　49.4%　than　the　complete　J-1　and　J-2　joints,　the　bearing　capacity　increases　25.2%　and　67.8%,　and　the　stiffness　increases　27%　and　34%　respectively.The　displacement　ductility　of　GJ-1　and　GJ-2　is　100%　of　J-1　and　93.1%　of　J-2,　respectively.It　can　be　seen　that　the　method　proposed　can　effectively　improve　the　seismic　performance　of　the　earthquake-damaged　PC　frame　structure.　©　2020,　Editorial　Board　of　Journal　of　Huazhong　University　of　Science　and　Technology.　All　right　reserved.