Automatic nesting optimization can improve the material utilizing rates and nesting efficiencies, but original designing data must be pre-processed, such as basic workpiece split/combination. Considering automatic nesting optimization, the requirements for sheet workpiece split/combination and requirements for data pre-processing were analyzed firstly. Then a solution for split/combination data pre-processing was proposed according to requirements above. As a result, the pre-processing module was developed and implemented. The efficiency of process designing was improved which provided accurate data for nesting optimization module, so that it becomes available to optimize nesting automatically and calculate material quota accurately.