The objective of this study attempts to evaluate the diversity of Coix germplasm resources by phenotypic chracters and thus provide basis for parent selection and variety improvement.A total of 22 phenotypic traits were investigated on 108 Coix L. germplasm accessions, which contained two species and four varieties of Coix L. The genetic diversity of 9 descriptive traits (colour of coleoptile, seaf sheath, seeding leaf, stigma, young fruit, presence of involucre, involucre shape and texture) ranged from 0.55～1.65.The variation coefficients of 12 numerical characters (plant height, grain layer, stem diameter, length of leaf, width of leaf, total tillers per plant, productive tillers per plant, nodes on main stem, branching node, 100-fruit weight, involucre length and involucre width) ranged from 13.0%～60.1%. Moreover, most of numerical traits related significantly to each other, and five principle componence were extracted and simplified from the phenotypic traits with a cumulative percentage of 77.4% by principle componence analysis. By cluster analysis, these acceccsions were clarified into three groups, including: group-I, in which these accessions showed dwarf plants, smaller leaf, fewer nodes and lower branching nodes, and in which they were distributed in the higher latitude areas; group-II, in which these accessions were distributed in the lower latitude areas of the middle and lower reaches of Yangtze river, south and southwesr of China and southeast Asia, showing medium plant height, fewer tillers, stem diameters, nodes and branching nodes, leaf sizes there; group-III, in which the accessions were distributed in southwest of China, with the higher plants and thicker stem diameter, larger leaf size, more nodes and higher branching nodes, more tillers and higher biomass. Thus, by taking use of this collection with regional peculiarity and distinct phenotypic variation, this work might provide insight for selecting parental materials being valuable in breeding for elite adlay.