Abstract: The ornamental quality of Dahlia pinnata Cav. in Xi'an Botanical Garden was evaluated to provide references for the cultivation and breeding of D. pinnata Cav. in Xi'an. The main characteristics of fifty Dahlia species such as flower diameter, pedicel length, plant height and single flowering period were evaluated by grey system. After dimensionless treatment, the ornamental quality of Dahlia in Xi'an was evaluated and sorted by grey correlation analysis. The results showed that the correlation degree of Yun Look Lotus Peak,Love in snow with ideal species was 0.80. The comprehensive performance of index factors was the best, and the ornamental quality of Dahlia was the best. According to the characteristics of Dahlia cultivars, the application suggestions were put forward.

Key words: Dahlia pinnata Cav., grey relational analysis, ornamental evaluation, Xi'an area