Abstract: For the purposes of rural road concrete pavement slab size optimization, the reduction of slab thickness has the advantage of lowering construction cost. This paper studied the slab size and thickness under positive and negative temperature gradients, and the most adverse locations in slabs where the traffic load is applied. This study conducted the finite element analysis for slabs on Winkler foundation. The research results show that: the slab size influences the maximum tensile stress developed in the slabs more than the thickness, and the thickness can be reduced by decreasing the slab size; small-bay slabs are those slabs that are only subject to the wheel loads, and the critical size of small-bay slab is 2.0 m×2.0 m; the modulus of subgrade reaction has minor impact on the maximum tensile stress of the small-bay slab; for the small-bay slab, when fatigue damage is considered, the critical thickness is 19 cm and 16 cm under positive and negative temperature gradients (15℃and -15℃), respectively. The results may provide a reference to the rural road pavement structure optimization design, which leads to cost saving.