The present disclosure provides a power module assembly and a converter. The power module assembly includes a power module and a capacitor module, and the power module and the capacitor module are configured to be detachably connected; the power module includes a first bus bar, and the first bus bar includes a first connection portion and a power installation portion connected to the first connection portion; the capacitor module includes a second bus bar, and the second bus bar includes a second connection portion and a capacitor installation portion connected to the second connection portion, wherein the first connection portion and the second connection portion extend along a first direction, and the power installation portion and the capacitor installation portion extend along a second direction; the first connection portion and the second connection portion are connected by a fastener.