This　work　investigated　the　local　buckling　failure　of　high-strength　and　large-diameter　pipelines　containing　a　dent　under　bending　moment.　An　improved　three-dimensional　numerical　model　was　developed　by　considering　the　multiple　nonlinearities　of　pipe　geometry,　material　and　the　boundary　conditions.　The　effect　of　yield　strength　and　strain　hardening　parameters　of　pipeline　steel　on　the　critical　buckling　load　at　the　dent　was　analyzed　in　detail.　The　results　show　that,　the　critical　buckling　moment　of　the　pipeline　decreases　with　the　increase　of　n.　However,　when　the　internal　pressure　is　low,　the　influence　of　internal　pressure　on　the　critical　buckling　moment　is　limited,　and　the　hardening　exponent　affects　the　critical　buckling　moment　only　when　n　＜　24.　The　greater　the　internal　pressure,　the　faster　the　critical　bending　moment　decreases　with　the　strain　hardening　exponent,　especially　when　the　circumferential　stress　of　the　pipeline　exceeds　the　yield　strength　of　the　steel.　The　sensitivity　analysis　of　the　size　parameters　of　dents　indicates　that　the　large　and　deep　dent　can　significantly　reduce　the　bending　moment　resistance　of　a　pipeline.