This study attempted to investigate the phenotypic variation at nine plant architecture related traits (including plant height, stem diameter, and leaf related traits), via accurate identification and comprehensive evaluation of 371 domestic sorghum accessions, followed by the coefficient of variation, correlation analysis, cluster analysis, principal component analysis, and affiliation function F-value evaluation methods. Based on the phenotypic datasets from two years at two locations, the mean coefficient of variation ranged from 10.14% to 35.70%, and the genetic diversity index ranged from 1.94 to 2.14. These results revealed rich phenotypic variations in the germplasm collection, and visible variations for particular traits including internode number, the leaf angle of the second and third leaf from top, and stem diameter under environmental conditions. Based on cluster analysis, sorghum accessions were divided into three groups: Group I was medium-culm spreading and medium-culm compact plants, Group II was tall-culm spreading plants and Group III was short-culm compact plants. The nine traits were divided into four principal components by principal component analysis. The first principal component was mainly the straight stem, the leaf width of the second and third leaves from the top, and the number of internodes, with a contribution of 36.424%. The fourth principle component consisted mainly of the angle of the second leaf from the top, with a contribution of 11.132%. Stepwise regression analysis identified plant height, internode number, stem diameter, and the leaf angle of the second leaf from the top as the main traits that could be used for plant type analysis. Thirty elite germplasm resources, including ‘103’, ‘Beijing Selection No.1’, ‘44F’, and ‘714R’, were selected using the integrated evaluation method of the affiliation function in combination with breeding objectives. Through the comparison of traits between different sorghum variety categories, it is found that the improved varieties have a clear trend towards dwarfism, compactness, and resistance to overturning, which are more suitable for modern production requirements.