The characteristics of alfalfa growth in the semi-arid sandy area for different buried depths of underground drip irrigation are studied.Effects of the buried depths on alfalfa planTheight, root collar diameter, branch number per plant, root length, weight density, and yield are investigated experimentally.Principal component analysis is used for comprehensive evaluation.Results show that the dropper installed at different depths affects the indexes of various alfalfa growth characteristics.In the seedling stage, the 10 cm laying depth treatment is conducive to alfalfa growth.From the branching period, the 30 cm laying depth treatment is superior to other treatments.T hroughout the growth period, the buried depths rank in the descendant order of 30, 20, 10, and 40 cm in terms of the comprehensive evaluation for the effects of different laying depths on alfalfa growth characteristics.