A sealing structure for a Stirling cooler includes a bellows, a first connecting block disposed at an end of the bellows, and a second connecting block disposed at another end of the bellows. The sealing structure for a Stirling cooler can generate both off-axis movements and lateral movements so as to produce corresponding harmonic motions, such that vibrations can be isolated, excellent vacuum can be obtained, and superior sealing quality can be ensured. Thereupon, possible leakage for the Stirling cooler operated under a significant pressure difference can be substantially resolved.