This study demonstrates the isolation performance of a non-linear passive isolator to enhance the pointing performance through isolating disturbances induced by a spaceborne cryogenic cooler. In this paper, a non-linear passive isolation system with varying stiffness under launching and under on-orbit conditions to attenuate the micro-vibration of the cooler is proposed. The isolation system provides low stiffness for small excitation of the cooler during on-orbit operation and high stiffness when the excitation range is relatively larger under the launch environment. The performance of the passive isolation system is investigated through both a launch environment test and a micro-vibration measurement test of the cooler combined with non-linear passive isolators.