Tension leg platform (TLP) is a suitable type for very deep-water oil production. The TLP is a compliant structure behaving like a floating one. It can be modeled as a rigid body with six degrees of freedom (6-DOF), which can beconveniently divided into two categories, those controlled by the stiffness of tethers, and thosecontrolled by the buoyancy. The former category includes motion in the vertical plane and consistsof heave, roll and pitch (stiff DOF); whereas the latter comprises the horizontal motions of surge, sway andyaw (flexible DOF). This paper investigates the nonlinear response of the Square TLP configuration under different random wave approach angles, 0o and 30o. Random waves were generated according to Pierson-Moskowitz spectrum and acts on the structure in the surge direction. The hydrodynamic forces evaluation is based on the modified Morison equation. Coupling effect and added mass are considered in the developing of the equation of motion. The nonlinear equation of motion is solved in the time domain utilizing the modified Euler scheme. Time history responses, phase planes, and Power spectrum densities (PSD) for the nonlinear responses for both approach angles are shown. It was found that, Variation of wave approach angle activates specific degrees of freedom like sway and roll which otherwise are not activated under unidirectional wave force.