The　effects　of　the　vent　burst　pressure　(Pv)　on　the　vented　explosion　of　hydrogen-methane-air　mixtures　are　investigated　in　a　cylindrical　vessel　connected　with　a　duct.　The　results　demonstrate　that　Pv　significantly　affects　the　flame　behaviors　and　overpressure　inside　and　outside　the　venting　configuration.　The　flame　front　velocity　at　the　vent　increases　with　Pv.　Two　pressure　peaks,　Pac,　caused　by　the　acoustically　enhanced　combustion,　and　Pse,　caused　by　the　secondary　explosion,　dominate　within　the　vessel　at　Pv　＜　132　kPa　and　Pv　＞=　132　kPa,　respectively.　The　maximum　overpressure　(Pmax)　inside　the　duct　increases　with　Pv.　The　maximum　pressure　rise　(dp/dt)　of　the　duct　is　always　higher　than　that　of　the　vessel.　As　Pv　increases,　increased　turbulence　of　unburned　gases　within　the　duct　results　in　higher　dp/dt.　Exit　flame　speed　increases　with　Pv.　When　Pv　＞=　153　kPa,　＂Mach　disk＂　appears　outside　the　relief　duct.　Three　pressure　peaks,　Pa,　Pb,　and　Pext,　due　to　vent　failure,　the　secondary　explosion,　and　the　external　explosion,　respectively,　occur　in　the　external　pressure　curve.　Pb　dominates　outside　the　configuration　except　for　Pv　=　153　kPa.