An overturn structure of a footstep of a folding ladder, includes a footstep is disposed between two legs, wherein further comprising two pivot elements and a reinforcing bar connecting between the two legs, the pivot elements are respectively connected to both ends of the reinforcing bar, the pivot elements are pivoted joint to the footstep to make the footstep overturn about the reinforcing bar to fold and unfold, when the footstep is unfolded, the reinforcing bar is supported on the bottom portion of the footstep. The pivot elements are connected to the reinforcing bar, the pivot elements are pivoted joint to the footstep, the footstep can rotate about the reinforcing bar to fold and unfold, so that the structure is stable, when the footstep is unfolded, the reinforcing bar is supported on the bottom portion of the footstep, it thus significantly improves the bearing performance of the footstep.