Abstract: The discrete degree of the main characters of nuts yielded from 134 walnut plus trees preliminarily selected from the northeast part of Yunnan Province was analyzed. It was showed that there were great differences in the 7 major criteria of the nut among the 30 reselected walnut plus trees, i.e., the content of crude protein, content of crude fat, the mean value of three diameters, single fruit weight, nut kernel weight, shell thickness and the kernel ratio. The Principal Component Analysis with the 7 major criteria showed that the cumulative variance percentage of the 4 criteria including the nut weight, kernel weight, content of crude protein and fruit size reached 89315%. 4 function equations of the principal components were formulated. 10 superior trees were finally screened out based on the integrated evaluation of the important values of principal components and variance percentages of these trees. The theoretical results were verified with practical indices.