In order to explore the stiffness degradation of tram track slab caused by the combined action of tram load and uneven settlement, based on damage-finite element fully coupled method, a tram-subgrade coupling dynamic model was established, and the damage field evolution was introduced into the stress field of the concrete, the influence of uneven settlement wavelength, amplitude, and tram load on the fatigue damage accumulation of tram track slab concrete were investigated, then from the perspective of the tram track slab service condition, a control threshold for the tram track subgrade settlement was proposed. The results showed that uneven subgrade settlement will accelerate the damage of the tram track slab concrete; as the tram speed increased, the track slab service life gradually decreased, and the calculation results of damage-finite element fully coupled method can better reflect the mutual influence mechanism between the tram track slab damage and stress field, the fatigue damage mechanism of the track tram slab was revealed to a certain extent.