Case retrieval is an important issue of the Cased Based Reasoning(CBR). To improve the accuracy of case match with inadequacy information, the grey relational analysis is employed to calculate the case similarity, and the computation formula of grey relational degree is ameliorated. A new case retrieval algorithm based on two-step search strategy is proposed. The comparison of the different retrieval algorithms is reported. The result shows that this method has high discernment, and overcomes the limitation of the traditional method, which has more subjectivity in deciding the similarity coefficient.