Abstract: In this paper, the paper folding problem is simplified to a three-point bending model of a simply supported beam with a rectangular cross section under the concentrated force acting on the middle position. The maximal folding times of a sheet of A4 printing paper and octavo newspaper under a normal human force are related with the maximum bending deflections and the minimum folding loads. The results show that for an ordinary A4 printing paper, an adult can only fold 6 times, or up to 7 times under extreme circumstances. For an octavo newspaper, an adult can easily fold 7 times, but not 8 times. The test results are in good agreement with the theoretical predictions.