Abstract: An electromagnetic clearance joint and an assembly method thereof are provided, the joint includes a mandrel and a shell. An inner diameter of the shell is larger than an outer diameter of the mandrel, the mandrel includes a first structure part and a second structure part which are connected to each other, and the shell includes a third structure part and a fourth structure part which are connected to each other. A plurality of acting grooves are evenly and circumferentially distributed around the first structure part. An outer diameter of the first structure part is gradually reduced, a plurality of annular ridges are sequentially distributed axially on the outer surface of the second structure part and form the ridge structures, a plurality of grooves axially extending are arrayed circumferentially on the outer surface of the second ridge structure.