Because of desired mechanical and physical properties, aluminum is the most widely used non-ferrous metal in industry and engineering applications. By changing the chemical composition of aluminum, its properties can be changed to achieve the desired properties. As technology advances, for use of several properties of aluminum alloy simultaneously, engineers thinking to use of bimetal or trimetal composite parts. Many different methods have been used to produce these parts which casting method, especially compound casting is the best option in terms of creating a perfect metallurgical bond. The basic requirement in the production of casting these parts is establishing a firm connection between the two metal. In bimetallic parts that one of the metals is aluminum, aluminum oxide prevented from creating such a connection that with chemical preparation and remove the oxide layer, this problem has been fixed. However, this solution requires special equipment for coating which increases the difficulty, time and cost of the process. In this study, the production of aluminum-aluminum bimetal with A356-7075 alloys using compound casting without surface preparation of insert was successful and the interface between the two metals were characterized. For this purpose, three different molds for casting samples were used and the effects of how the melt into mold, melt temperature, insert temperature, the cooling conditions and surface conditions of insert was evaluated on the quality of the interface. Then the samples were characterized. The microstructure of interface was analyzed using an optical microscope. The mechanical properties of the interface with the outside and micro-hardness tests were evaluated. The mechanical properties of the interface were evaluated with push-out and micro-hardness tests. Surface combination of the alloys is also investigated by line scan elemental analysis using a scanning electron microscope. The results showed that the vertical casting due to temperature drop, the interface is uniform throughout the sample. So that, pressureless horizontal casting method in sand mold with entry of melt from beside of sample, melt temperature 720°C and polished insert (with sandpaper) give the best results. The push-out test results indicated uniform shear strength in the samples that were built horizontally. Also the instance sample was made on equal terms and without any surface preparation for investigating of surface roughness effect on the quality of the interface. The results show that the surface roughness with increasing thermal shear stress applied to the thermal oxide film by the melt and help break it, increase the interface shear strength of more than 120 percent.