Welding arc deposition is a high efficient rapid forming technology which can be used to rapidly form metal functional parts directly. While, Traditional slicing methods in the rapid forming process always produce ‘staircase’ or additional support structure which reduce deposition accuracy and efficiency, bring about the dissipation of materials. Even that it cannot exploit the advantages of welding arc deposition method. This paper proposes a slicing strategy which is suitable for rapid forming based on welding arc deposition. During slicing stage, the CAD model is decomposed into different pieces based on its geometrical feature to make each piece can be deposited in one direction without support structure, and layer thickness is determined according to the height of each sub volume and welding parameter database. A typical part is built with this method. It shows that this method is feasible and high efficient.