Incomplete data samples have a serious impact on the effectiveness of data mining.Aiming at the LRE historical test samples,based an correlation analysis of condition parameter,this paper introduced principle component analysis (PCA)and proposed a complete analysis method based on PCA for incomplete samples.At first,the covariance matrix of complete data set was calculated; Then,according to corresponding eigenvalues which were in descending,a principle matrix composed of eigen- vectors of covariance matrix was made; Finally,the vacant data was estimated based on the principle matrix and the known data.Compared with traditional method validated the method proposed in this paper has a better effect on complete test samples.An application example shows that the method suggested in this paper can update the value in use of historical test data.