Abstract: Soil salinity and drought are important factors affecting the production of high-quality forage in southern Xinjiang, thus restricting the development of herbivorous animal husbandry. Five rapeseed varieties were used in this study to screen out the forage rape varieties suitable for planting under forest in southern Xinjiang. Five mannitol levels (0, 100 mmol·L⁻¹, 200 mmol·L⁻¹, 300 mmol·L⁻¹ and 400 mmol·L⁻¹) were designed to simulate drought levels. NaCl, Na₂SO₄ and NaHCO₃ were mixed at a ratio of 1∶2∶1 to design 5 salt levels (0, 50 mmol·L⁻¹, 100 mmol·L⁻¹, 150 mmol·L⁻¹, and 200 mmol·L⁻¹). The germination characteristics of seeds were analyzed. The understory planting test was carried out with a randomized block test, and the in vitro fermentation experiment was carried out with a completely randomized design to analyze the biomass yield and nutritional quality of forage rape. The results showed that when the mannitol concentration was 400 mmol·L⁻¹, the germination rate of Xinyou17 was the highest (92.7%) followed by Qingyou21 (91.3%). The Shaoyou28 had the highest germination rate of 74.7% when the compound salt concentration was 100 mmol·L⁻¹, followed by Huayouza76 (65.0%). The hay yield of Huayouza76 was up to 5.25×10³ kg·hm⁻². The Shaoyou28 had the highest total gas production, dry matter degradability and total volatile fatty acid concentration in thein vitro fermentation. The gray correlation value between hay yield and nutrients was the largest in HF808, followed by Qingyou21 and Huayouza76. Qingyou21 exhibited better drought resistance, while HF808 and Huayouza76 were tolerant to salt stress which all had higher production capacity. These varieties may better adapt to the growth environment under forest in the arid and saline areas of southern Xinjiang, and were suitable for planting under forest in southern Xinjiang.