A method for preparing a Josephson junction, performed by a production line device, comprising: preparing (201; 501) a circuit structure on a substrate by nano-imprinting; the circuit structure comprising a first lead (31; 41; 61; 71), a second lead (32; 42; 62; 72), and a peripheral circuit connected to the first lead (31; 41; 61; 71) and the second lead (32; 42; 62; 72); and the first lead (31; 41; 61; 71), the second lead (32; 42; 62; 72), and the peripheral circuit being of an integral structure; preparing (202; 502) a photoresist-based undercut structure on the substrate; the undercut structure being a strip-shaped structure, and the undercut structure comprising a first region (33; 44; 63a; 73a), a second region (35; 45; 63b; 73b), and a third region (34; 46; 63c; 73c) connected between the first region (33; 44; 63a; 73a) and the second region (35; 45; 63b; 73b); the first region (33; 44; 63a; 73a) and the second region (35; 45; 63b; 73b) having upper photoresist layers and lower layers of hollow-out; the third region (34; 46; 63c; 73c) being an opening region of the undercut structure; the first region (33; 44; 63a; 73a) covering an end of the first lead (31; 61; 71); the second region (35; 45; 63b; 73b) covering a portion of the second lead (32; 62; 72); and the third region (34; 46; 63c; 73c) being located between the first region (33; 44; 63a; 73a) and the second region (35; 45; 63b; 73b); preparing an oxide layer on a surface of the second lead (32; 42; 62; 72) which is not covered by the photoresist; evaporating (204; 505) a first superconducting layer obliquely in a direction from the first region (33; 44; 63a; 73a) to the second region (35; 45; 63b; 73b) to obtain the Josephson junction; and the first superconducting layer covering a region on the second lead (32; 42; 62; 72) which is not covered by the photoresist and a portion of the substrate between the second lead (32; 42; 62; 72) and the first lead (31; 41; 61; 71); and evaporating (205; 507) a second superconducting layer obliquely in a direction from the second region (35; 45; 63b; 73b) to the first region (33; 44; 63a; 73a); and the second superconducting layer covering a region on the first lead (31; 41; 61; 71) which is not covered by the photoresist, the portion of the substrate between the second lead (32; 42; 62; 72) and the first lead (31; 41; 61; 71), and a portion of the first superconducting layer. preparing (201; 501) a circuit structure on a substrate by nano-imprinting; the circuit structure comprising a first lead (31; 41; 61; 71), a second lead (32; 42; 62; 72), and a peripheral circuit connected to the first lead (31; 41; 61; 71) and the second lead (32; 42; 62; 72); and the first lead (31; 41; 61; 71), the second lead (32; 42; 62; 72), and the peripheral circuit being of an integral structure; preparing (202; 502) a photoresist-based undercut structure on the substrate; the undercut structure being a strip-shaped structure, and the undercut structure comprising a first region (33; 44; 63a; 73a), a second region (35; 45; 63b; 73b), and a third region (34; 46; 63c; 73c) connected between the first region (33; 44; 63a; 73a) and the second region (35; 45; 63b; 73b); the first region (33; 44; 63a; 73a) and the second region (35; 45; 63b; 73b) having upper photoresist layers and lower layers of hollow-out; the third region (34; 46; 63c; 73c) being an opening region of the undercut structure; the first region (33; 44; 63a; 73a) covering an end of the first lead (31; 61; 71); the second region (35; 45; 63b; 73b) covering a portion of the second lead (32; 62; 72); and the third region (34; 46; 63c; 73c) being located between the first region (33; 44; 63a; 73a) and the second region (35; 45; 63b; 73b); preparing an oxide layer on a surface of the second lead (32; 42; 62; 72) which is not covered by the photoresist; evaporating (204; 505) a first superconducting layer obliquely in a direction from the first region (33; 44; 63a; 73a) to the second region (35; 45; 63b; 73b) to obtain the Josephson junction; and the first superconducting layer covering a region on the second lead (32; 42; 62; 72) which is not covered by the photoresist and a portion of the substrate between the second lead (32; 42; 62; 72) and the first lead (31; 41; 61; 71); and evaporating (205; 507) a second superconducting layer obliquely in a direction from the second region (35; 45; 63b; 73b) to the first region (33; 44; 63a; 73a); and the second superconducting layer covering a region on the first lead (31; 41; 61; 71) which is not covered by the photoresist, the portion of the substrate between the second lead (32; 42; 62; 72) and the first lead (31; 41; 61; 71), and a portion of the first superconducting layer.