A certain automobile engine block is taken as a research object. Based on the analysis of processing requirements and existing problems in production lines, special machine tools and processes are selected and designed. A process plan for onetime clamping doublesided multiaxis simultaneous machining is presented by adoption of the principle of process concentration. The layout scheme was determined according to the process plan. The layout plan is that the special fixture is set in the middle of the special machine bed, the auxiliary loading and unloading station is set at the front of the machine, and a multiaxis special spindle box is set at the left and right ends of the machine. According to the requirements of the processing attitude, a special clamp positioning and clamping scheme and its overall structure are designed, and its working principle is elaborated in detail. The actual production shows: after adopting this technology and equipment, the actual annual production schedule of a single device has increased from about 50 000 to about 330 000, and the qualification rate has increased from about 90% to more than 99.9%. All the indicators have reached the production needs of enterprises.