When　using　offshore　rotating　platforms　for　deep-sea　operation,　coiled　tubing　(CT)　is　affected　by　both　the　ocean　load　and　torque.　Moreover,　the　variation　law　of　axial　force　complexity　increases　when　the　CT　is　in　a　helical　post-buckling　state.　Therefore,　in　this　paper,　a　＇pipe-in-pipe＇　system　test　bench　was　built　to　simulate　the　effects　of　ocean　loads　and　torques　on　the　CT.　A　helical　post-buckling　state　was　reached　and　the　axial　force　variation　law　was　analyzed.　The　results　have　shown　that　both　the　ocean　load　amplitude　and　the　initial　torque　increased　the　axial　force　fluctuation　of　CT.　The　torsion　direction　of　helical　post-buckling　was　determined　by　the　direction　of　applied　torque.　Additionally,　given　the　equal　injection　force,　the　greater　the　torque,　the　greater　the　helical　post-buckling　degree　of　CT　and　the　lower　the　axial　force　transmission　efficiency.　Obtained　results　supplement　the　theoretical　system　of　pipe　mechanics　and　improve　the　operation　efficiency　of　offshore　rotating　platforms.　©　2022　Elsevier　Ltd