Abstract: In order to study the triaxial compressive mechanical properties of glass fiber coral seawater concrete, 36 glass fiber coral seawater concrete cylindrical specimens were subjected to conventional triaxial loading tests. The damage morphology of the specimens was observed, and the stress-strain curves were obtained. Based on the test data, the influence of the surrounding pressure value and glass fiber admixture on the mechanical properties was analyzed. The results show that the damage pattern changes from vertical splitting to oblique shear and central extrusion flow damage as the surrounding pressure increases. The slope of the rising section of the stress-strain curve increases, the peak section increases, and the falling section after the peak point gradually disappears, and the corresponding initial elastic modulus, peak strain, peak stress and energy dissipation increase, while the ductility coefficient shows a trend of first increasing and then decreasing, when the confining pressure value is 6 MPa, the ductility coefficients are 3.64 times, 3.32 times and 2.86 times respectively in the uniaxial pressure state. The average values of modulus of elasticity, ductility coefficient, peak stress and energy dissipation all show a trend of increasing and then decreasing, while the average peak strain shows a trend of decreasing and then increasing, when the glass fiber dosage is 4 kg·m⁻³, the average modulus of elasticity reaches 5.83 GPa, which increases the average ductility coefficient by 3.0% and 16.7% and the average peak stress by 9.6% compared with the other two dosages. The lateral surrounding pressure and external glass fiber doping can reduce the development speed and degree of damage, and the lateral surrounding pressure can also delay the appearance of initial damage.