在白车身工艺规划过程中，积累了大量车身焊接工艺数据。为了提取这些知识采用数据挖掘方法发现其中所需的工艺规则。首先采用粗糙集对工艺属性进行约简，删除对工艺决策没有影响的属性；然后采用关联规则挖掘对焊接方法有影响的工艺规则；最后用实例验证了该方法的有效性。“,”Large quantities of data are accumulated in process planning for body in white( BIW). To acquire the potential and valuable process knowledge from these data,the rough set theory and association rule technique are integrated to discover the useful correlations between the welding type and process requirements. The correlations can guide us to select the welding type according to the given process requirements. During data mining,every process requirement is regarded as an attribute. First,the decision table for the welding type is constructed. Sec-ond,rough set theory is employed to remove redundant attributes. A simplified decision table is constructed. Third,association rule is used to extract the useful rules. Finally,an illustrative example indicates this methodol-ogy can extract useful rules for the selection of welding type.