There are several possibilities for establishing a cohesion joint between dissimilar metals. In the case of thin sheets, the ultrasonic welding process is suitable. This process can establish a cohesion joint rapidly, with a low heat input between the thin sheets. The authors have tried to determine the optimal ultrasonic welding parameters for copper and austenite stainless steel joining by using an experimental method of joining. Suitable results were obtained by welding tests due dissimilarities in the chemical, physical and mechanical properties of the copper and stainless steel. A standard size sheet thickness and test sample was used for the welding by different parameters. The parameters were refined based on the theoretical and practical knowledge during the experiments. The experimental welding was made by a Branson L20 type welder machine. The joint made by the different parameters was inspected by shearing-tensile tests (maximal force level).