Base isolation is a broadly accepted and used technique to protect structures against ground motions. In this research, TFPS (Triple Friction Pendulum System) is used to isolate Cable Stayed Bridge with length of 2000 ft. The aim of this research is to find out behaviour of cable stayed bridge under triaxial ground motions. Generally, effect of only uniaxial earthquakes are considered, but structures should also be stable when triaxial earthquakes hits the structure. If structure is stable in triaxial motions then it must be stable in uniaxial and biaxial ground motions. Uniaxial, biaxial, and triaxial Earthquake ground motions are applied to the bridge and time history analysis of two different ground motions is carried out. The behaviour of bridge undertriaxial ground motions are evaluated in SAP2000 software. Results of base-shear, bearing displacement, hysteresis behaviour, top of pylon displacement, and deck acceleration are compared after carrying out the analysis. Base shear was found highest in triaxial ground motions than uniaxial and biaxial ground motions.