Abstract: This paper introduces the design of an automatic rough machining line for engine block, it takes compact machining center as the main processing equipment, matches with horizontal machining center and special machine to form flexible production line, and adopts industrial robot with ground rail for loading and unloading. Through the optimization of robot gripper, machine tool transformation, rotary table, hydraulic fixture and special tool, the production line integrates automation, lean technology and information technology, it is advanced and economical. With less than 40% investment, the same capacity of the traditional cylinder production line will be achieved. The number of personnel will be reduced to only 1 people per class, and the direct processing cost of single parts will be reduced by 30%.