Resistance spot welding is a worldwide used welding technology that is particularly important for the vehicle industry. The main purpose of my current paper to determine the influence of the changing parameters on the strength of resistance spot welded joints in case of DC03 cold-rolled steel sheets. Parameters like welding current, welding time, electrode force and number of repetitions of welding cycles are the essential parameters which plays a crucial role in resistance spot welding. It is quite demanding to determine applicable welding parameters for different materials. In this paper the tensile shear tests are done and determined how the changing parameters will affect the tensile strength and elongation of the material joined. The results of this paper are very significant for the welding industry. The resistance spot welding technology is widely used in the automotive industry, aerospace industry, household appliances and electric vehicle battery production, therefore technological optimization promotes production efficiency and improves the quality and reliability of manufactured products.