A branched stent graft comprises a main body portion and a branch portion. Each of the main body portion and the branch portion includes a stent and a tubular graft. The stent of the main body portion includes a plurality of stent segments, at least one of which is a varying-height stent segment (102). The stent of the branch portion includes one or more stent segments, at least one of which is a varying-height stent segment (103). The distance between the proximal-most stent segment of the branch portion and the main body portion is in the range of 2-8 mm. A positioning ring (105) may be used at a side opening which connects the branch portion and the main body portion, and the positioning ring (105) can be sutured inside the graft of the main body, between the graft of the main body and the graft of the branch, or outside the graft of the branch.