Abstract:The excavator working device EER data model was built based on the database technology.The whole part of working device instance library was designed by using of the objectoriented expression method based on EER data model,at the same time using Case Based Reasoning (CBR) technology to search the product case data and put forward the corresponding strategy of correction.Through the similarity calculation between instance objects searching similar instance,and correct the similarity for the similar parts,with characteristic values determining the scope of the case similarity,the instance correction method was determined.Finally,VC language is used to develop the excavator working device instance library system,which is applied to practical production.