Abstract: Strength of resistance spot weld is determined by the physical attributes of weldment including material and geometric issues.The strength of the ring nugget in sheet-to-tube single-sided spot welding is different from that of the button nugget in traditional sheet-to-sheet spot welding.And the relationships between strength and attributes of ring nugget are unknown.Meanwhile, the large number of variables and experimental uncertainty also make it difficult to establish this relationships.A numerical simulation experiment was conducted using the concept of design of experiments (DOE) and the method of finite element based on the tensile-shear tests.The mechanical properties during tensile-shear process was analyzed and quantitative relationships were established to link a weld's tensile-shear force and its geometrical attributes, which supplied the proof for the nugget quality estimation.