Abstract: 【Objective】 This project aims to study the effects of drought stress and sowing density on the physiological characteristics and yield of onion bulblets in order to explore the use of onion bulblets as sowing materials in the hope of laying a theoretical and technical foundation for the mechanized planting of onion. 【Methods】 ' Baixue ' was used as the experimental material, and the flat-bottom seedling tray was used for sowing. Three sowing densities were designed : 1.5 cm × 1.5 cm(A₁), 2 cm × 2 cm(A₂) and 2.5 cm × 2.5 cm(A₃). Three kinds of drought stress : 8 % field capacity(B₁), 13 % field capacity(B₂) and natural drought(B₃). 【Results】 With the increase of drought stress duration, the plant height and pseudostem diameter of onion seedlings increased first and then decreased. Appropriate drought stress promoted the growth of the transverse diameter of underground onion bulblets. The soluble solids content of onion treated with (2 cm × 2 cm) * natural drought (T₆) was the highest, which was 20.17 %. The soluble sugar content of 8 % (T₄) treatment of (2 cm × 2 cm) * field capacity was the highest, which was 6.73 %. With the increase of sowing density, soluble protein content and CAT activity showed an increasing trend, but the difference was not significant. The POD activity of (2 cm × 2 cm) * natural drought (T₆) treatment was the highest, which was 23.6 (U/(g·min)); the highest SOD activity was 7,560 (U/(g·h)) under (1.5 cm × 1.5 cm) * natural drought (T₃) treatment. The number of bulblets in (1.5 cm × 1.5 cm) * 3 drought (T₁-T₃) treatments was significantly higher than those in other treatments, and the number of bulblets per square centimeter was 36.13, 35.05 and 35.48, respectively. The bulk density, total porosity, water holding porosity and EC values of the seedling substrate before and after drought were within the ideal range. The comprehensive evaluation value from high to low was T₉ > T₈ > T₇ > T₁ > T₆ > T₄ > T₅ > T₂ > T₃. 【Conclusion】 The comprehensive performance of (2.5 cm × 2.5 cm)* natural drought (T₉) treatment is good and ranks first, which can be used as a combination for cultivating onion bulblets.