Abstract: This paper discusses an interesting mechanical experiment of hanging weight with three matches, based on the equilibrium principle. It is a self-locking problem. The relationship between the maximum weight and the bending stiffness of the match, the friction coefficient between the match and the table, the size of the match and the layout of the match is obtained by the bending deformation theory of the beam. The influence of the friction coefficient and the distance between the cotton thread and the table on the ultimate load is analyzed with some examples.