Supporting structure for sliding rail that uses one or more identical modules, stacked longitudinally and supported on the beams of the conventional compact palletisation facility, on which the tracks for the chains of the sliding rail are subsequently mounted, each of these modules including, in turn, a quadrangular mesh supported on several ribs that may be fixed or telescopic, and which has, on its upper part, supporting rods for the rails for the chain. The supporting structure for sliding rail that is presented affords the main advantage of enabling any existing compact “drive-in” palletisation structure to be used and adapted to operate with “flow-rail” sliding rails or similar, dispensing with the need for custom adaptations, as well as achieving greater rigidity, better inner fitting, greater resistance to deformation and smoother operation of the sliding rail.