The invention provides a fuse unit and a unit body thereof. An incoming conductor used for being conductively connected with a contact at one end of a fuse and an outgoing conductor used for being conductively connected with a contact at the other end of the fuse are arranged on the unit body of the fuse unit. A mounting base used for mounting the contact at one end of the fuse and conductively connected with the contact is arranged in the unit body. The mounting base is conductively connected with the incoming conductor or the outgoing conductor. The mounting base is detachably connected in the unit body, and the position of the mounting base relative to the unit body in the length direction of the unit body is adjustable. An adjusting structure used for adjusting the position of the mounting base is arranged in the unit body. Only one specification of unit body needs to be manufactured for switch cabinets with different voltage levels. During assembly of the fuse unit, the mounting base is first adjusted to a proper position according to an adaptive voltage level, so that a fuse with a specific length can be mounted in the unit body. The adaptive voltage level can be changed by changing the position of the mounting base. There is no need to manufacture unit bodies with various specifications, and the manufacturing cost is greatly reduced.