The invention researches the substantive characteristics of material deformation to aim at the practical problem of measuring real stress-real strain and discloses a real stress-real strain calculating model and a practical testing system: 1, based on the analysis on the deformation of a tension specimen, taking a unit body the special part of which is provided with characteristics as the object for the stress-strain analysis, building a unique full-deformation unit model, firstly solving the theory analysis problem of real stress-real strain, establishing a theory foundation and building a novel real stress-real strain calculating formula: Sigma i is equal to 4Fi/Pi d<2>I and Epsilon is equal to (d<2>0/d<2>i) minus 1; 2, adopting a machine visual technology and an image processing method to develop a practical software system and a practical hardware system that are compatible with the machine visual technology and the image processing method, and realizing the direct non-contact real stress-real strain measuring in real meaning; 3, the testing system includes a light source (1), CCD camera (2), an image acquisition card (3), a data acquisition card (4) and a material testing machine (5); 4,the software includes image capturing program, load data acquisition program and comprehensive calculation analysis program.