Abstract: In order to make a full use of the potential of materials as well as to promote the classroom teaching for the course of mechanics of materials, the strength-stiffness ratio of beams is introduced in the paper. The ratio provides a quantitative relation between the strength and the stiffness of beams in the non-dimensional form. It is independent of the magnitude of load, its value can be obtained through the finite element method or through the load test of beams. Combined with the engineering practice, the strength-stiffness ratio of beams are analyzed with its influence factors from the aspects of design and test.