Abstract: As the development difficulty of oil and gas fields and the complexity of downhole situations increase, conventional cement sheath tends to suffer brittle failure and its interlayer isolation effect is impacted.And consequently, wellbore integrity is damaged.Sulphoaluminate cement is a kind of cement material with excellent properties.A sample of fiber glass reinforced sulphoaluminate set cement (CSA/GRC) was prepared to clarify its application potential in cementing engineering.The crystal hydration products of sulphoaluminate cement with different ages were analyzed by means of X-ray diffraction method.The mechanical property of CSA/ GRC set cement was tested by using triaxial stress-strain experiment.The microscopic morphology on the rupture plane of CSA/GRC set cement was observed under scanning electron microscope (SEM), and the toughening mechanism of fiber glass in sulphoaluminate set cement was investigated.It is indicated that CSA/GRC set cement has good toughness and mechanical deformation capacity and its axial compression strength and ultimate strain are about 45% and 300% higher than those of conventional fiber glass set cement.The combination between fiber glass and sulphoaluminate cement system is good and fiber is highly corrosion resistant.Fiber glass can restrict the further propagation of fractures by virtue of stress dispersion and bridging effect, so as to improve the toughness of set cement.