the　paper　presents　a　multi-joint　robotic　arm　with　light　weight　and　heavy　duty.　It　has　both　light　and　heavy　working　modes　of　operation.　Firstly,　the　motion　principle　is　analyzed　and　the　kinematics　model　is　established.　Through　TRIZ　theory,　the　range　of　each　articulated　arm　is　determined,　then　the　design　of　the　main　load-bearing　structure　is　carried　out.　The　ANSYS　simulation　analysis　is　carried　out　to　verify　the　rationality　of　the　structure.　Lastly,　the　transmission　mode　and　the　driven　motors　are　determined　and　the　prototype　is　produced.