On SWS 41 Plates jointed by the F11T M 20 high strength bolts the study on stress behavior and safety degree until rupture in static tensile tests were performed. By these results, in case of no clamping force stress concentration was extremed for strain of about 10% higher ratio. Elastic strain occurred to change of test specimens depth by the load and plastic strain occurred to local minute sleep after elastic strain. compared shear stress with tension stress from the fracture load it was showned lower values than the maximum shear stress theory and stress strain energy theory.