To　improve　the　arc　trajectory　planning　accuracy　of　manipulators,　a　new　trajectory　planning　algorithm　for　the　manipulators＇　position　planning　and　orientation　planning　is　presented.　First,　the　trajectory　curve　equation　of　welding　torch＇s　posture　meeting　welding　procedure　requirements　was　deduced　based　on　the　parameter　equation　of　the　circular　trajectory　for　large　components.　A　new　interpolation　algorithm,　which　meets　the　constant　welding　velocity　and　scheduled　approximation　error　though　changing　the　interpolation　cycle,　is　presented　for　the　pose　interpolation　of　circle　track　welding　on　large　components.　Finally,　it　takes　the　connection　form　of　a　large　plane　component　and　cylindrical　tube　for　example　to　illustrate　the　presented　algorthm　using　the　Mathematics　software.　The　simulation　results　show　that　the　presented　planning　algorithm　for　position　and　orientation　can　guarantee　the　continuousness　of　interpolation　and　improve　the　end　trajectory　precision　of　manipulator.　©,　2014,　Shanghai　Jiao　Tong　University.　All　right　reserved.