Herein,　the　ultrasonic　vibration　(UV)　technology　is　introduced　to　assist　the　warm　incremental　forming　of　magnesium　alloy　AZ31B　sheet.　The　corresponding　experimental　setups　for　UV-assisted　warm　tensile　test　and　incremental　forming　are　established.　The　effects　of　the　forming　temperature　and　UV　on　the　forming　force,　formability,　and　geometry　are　analyzed.　A　fully　thermal-mechanical　coupling-based　finite　elemental　model　is　established　to　simulate　the　forming　process.　The　model　takes　into　account　the　temperature　distribution　and　the　material　behaviors　affected　by　UV.　The　results　indicate　that　the　formability　of　the　magnesium　alloy　can　be　significantly　improved　under　conditions　of　UV　at　appropriate　temperatures.　The　effect　depends　on　the　coupling　effect　of　the　temperature　and　the　UV　amplitude.　The　simulation　and　experimental　results　are　compared.　The　merits　of　this　new　forming　technology　are　further　analyzed　following　simulation　and　experimental　conditions.