Taking fatigue crack of the welded metal bellows as an example, a method to add dampers to improve the capacity of the antifatigue cracks is presented based on the analysis of the dynamic model for mechanical seal to overcome the fatigue crack existing on the welded metal bellows for mechanical seal. The design specifications of the welded metal bellows for mechanical seal are given in this paper. The mechanical seal structure with dampers has passed the modal test, vibration test and assessment of the engine hot test, and has been applied successfully to the actual projects.