experiment course. Because of the simple preparation and easy measurement，the hand-crumpled

paper ball experiment is chosen by many students. In this paper the fractal in the

experiment of crumpled paper balls is discussed. The definition of fractal dimension is

introduced to describe the internal irregularity of the crumpled paper balls. The fractal

dimen- sion of normal A4 printing paper is measured experimentally and the influence of different

paper hardness and paper layers on the fractal dimension of paper ball is studied.