Abstract: Due to the existence of the Compressive Membrane Action (CMA) caused by its lateral restraints, the loading-carrying capacities and serviceability of concrete slabs can be enhanced significantly. In the investigation of the structural behaviour of concrete bridge deck slabs reinforced by fiber polymer reinforcements (FRP), an experimental study of a series of lateral restrained GFRP reinforced concrete slabs was carried out. In the experimental results, it was found that the behaviour of GFRP reinforced concrete slabs was influenced by horizontal restraint stiffness and concrete strengths significantly, but it was not affected by reinforcement percentages. However, the current design code (ACI-440 R06) underestimated ultimate strengths dramatically. Therefore, based on the previous research on concrete bridge deck slabs, a prediction method of loading-carrying capacities of GFRP reinforced concrete slabs was proposed. In the comparison of several experimental tests, a good collection between the theoretical method and experimental results was obtained.