<p>Hydraulic buffers, preferred for their long stroke and high energy absorption capacity, are widely used in transportation, aerospace, and defense systems. This study investigates a competitive failure reliability model with variable degradation rates for hydraulic buffers under different impact magnitudes. First, we analyze how variable impact magnitudes influence the degradation process and establish a reliability model that accounts for the competition between sudden failure and degradation failure. Next, we develop an advanced competitive failure reliability model that incorporates multiple impact magnitudes and variable degradation rates, considering the accelerating effect of the number of damage impacts and operational hours on the natural degradation. We then construct a fluid-structure interaction (FSI) finite element model of the hydraulic buffer and perform simulation analyses under multiple loading conditions to determine parameters for the reliability model. Finally, we compare various reliability models to assess their parameter sensitivities. The results show that the proposed competitive failure reliability model, which incorporates multiple impact magnitudes and variable degradation rates, indicates reliability more accurately for hydraulic buffers operating under complex and long-term impact conditions. This study may offer valuable theoretical insights for the optimal design and maintenance planning of hydraulic buffers.</p>