A suspension system for a vehicle may include a torsion beam disposed along width direction of the vehicle and including an attaching portion formed to an end portion thereof, a trailing arm disposed to the attaching portion of the torsion beam and aligned along length direction of the vehicle, wherein one end portion of the trailing arm is coupled to a wheel and the other end portion of the trailing arm is connected to a vehicle body, and a stiffener connecting the attaching portion of the torsion beam and the trailing arm disposed between the stiffener and the attaching portion of the torsion beam.