The twins suffered from malformed organs, according to Wang Weidong, the former head of the hospital.
"There was no successful separation operation on such rare conjoined twins before that time in China," Wang said in a Xinhua report. "But the boys could have died any minute if we hadn't performed the operation. I decided to take the chance to save their lives."
The risky surgery was carried out at the Xinqiao Hospital of Third Military Medical University in October 1996, after 20 days of preparation and research.
The 10-hour surgery was deemed a success, and the twins were name "Xin" and "Qiao" in honor of the hospital. Unfortunately, Gu Xin died about 20 days after the operation.
Gu Qiao passed his college entrance exam with a high score of 603, and was accepted to the Sichuan Foreign Studies University in Chongqing last week.
He returned to the hospital on Monday to extend his gratitude to the doctors, who he said "gave me the chance to fulfill my dream today".
Wang said during the reunion that he would contribute money to help pay for the student's tuition.