This paper briefly introduces the abnormal exhaust pressure problem of steam turbine, analyzes the reasons for the problem and puts forward some corresponding measures to solve the hidden problem caused by the unstable exhaust pressure of turbine to the normal operation of the plant during operation. The problems of air on the water side of condenser, corrugated pipe rupture and seal steam pipe breakage are introduced. By adopting correct treatment methods, the stability of exhaust pressure can be ensured, thus ensuring the stable operation of the ethylene plant.