A surgical device for osteotomy (1, 2, 3) comprising: a first body component (12, 22, 32) having an upper guide edge (122, 222, 321) and a first correcting perforation (123, 223, 322), said first correcting perforation (123, 223, 322) being connected to said first body component (12, 22, 32) by a first bar (224, 323); a second body component (14, 24, 34) having a lower guide edge (141,241, 341) and a second correcting perforation (142, 242, 342), said lower guide edge (141, 241, 341) disposed below said upper guide edge (122, 222, 321), a guide groove being formed between said upper guide edge (122, 222, 321) and said lower guide edge (141, 241, 341) for guiding a saw blade to perform a cutting procedure, said second correcting perforation (142, 242, 342) being connected to said second body component (14, 24, 34) by a second bar (243, 343); wherein a corrective angle (L, N) between a first hole axis of said first correcting perforation (123, 223, 322) and a second hole axis of said second correcting perforation (142, 242, 342) is formed, characterized in that said surgery device for osteotomy (1, 2, 3) is configured such that when an open angle of a gap of said osteotomy is the same as that of a preoperative planning correction angle, said first hole axis of said first correcting perforation (123, 223, 322) and said second hole axis of said second correcting perforation (142, 242, 342) will coincide, so that an alignment bar can be inserted between said first correcting perforation (123, 223, 322) and said second correcting perforation (142, 242, 342) only when a tibia is opened to said preoperative planning correction angle by said first body component (12, 22, 32) and said second body component (14, 24, 34). a first body component (12, 22, 32) having an upper guide edge (122, 222, 321) and a first correcting perforation (123, 223, 322), said first correcting perforation (123, 223, 322) being connected to said first body component (12, 22, 32) by a first bar (224, 323); a second body component (14, 24, 34) having a lower guide edge (141,241, 341) and a second correcting perforation (142, 242, 342), said lower guide edge (141, 241, 341) disposed below said upper guide edge (122, 222, 321), a guide groove being formed between said upper guide edge (122, 222, 321) and said lower guide edge (141, 241, 341) for guiding a saw blade to perform a cutting procedure, said second correcting perforation (142, 242, 342) being connected to said second body component (14, 24, 34) by a second bar (243, 343); wherein a corrective angle (L, N) between a first hole axis of said first correcting perforation (123, 223, 322) and a second hole axis of said second correcting perforation (142, 242, 342) is formed, characterized in that said surgery device for osteotomy (1, 2, 3) is configured such that when an open angle of a gap of said osteotomy is the same as that of a preoperative planning correction angle, said first hole axis of said first correcting perforation (123, 223, 322) and said second hole axis of said second correcting perforation (142, 242, 342) will coincide, so that an alignment bar can be inserted between said first correcting perforation (123, 223, 322) and said second correcting perforation (142, 242, 342) only when a tibia is opened to said preoperative planning correction angle by said first body component (12, 22, 32) and said second body component (14, 24, 34).