The sealing of deep shield tunnel and ventilation shaft is difficult and the demolition of a whole segment is of great risk after the Suzhou Metro shield tunnel directly passes through underground diaphragm wall with retaining structure of glass fiber and open-cut ventilation shaft filled by soil. Hence, a partial demolition scheme for segment is put forward, which demolishes upper part of segment and sets a horizontal beam to form a reverse-Ω structure. And then the influence factors of the construction is analyzed, the feasibility of the scheme is discussed in detail, some control measures are put forward, and the theoretical calculation and analysis are carried out on reverse-Ω structure. The results show that the scheme mentioned above is feasible and can reduce the construction rick effectively.