Abstract: 【Objective】 To select the best silage oat varieties suitable for planting and the best harvest time in Shihezi area by studying the nutritional quality and silage fermentation quality of five oat varieties (Souris, Qingyin 1, Longyan 2, Longyan 3 and charm) at two cutting stages (heading stage and milk stage) in experimental forage site of Shihezi University in Xinjiang. 【Methods】 Five oat varieties were mowed at heading stage and milk stage. After analyzing the indexes of fresh grass, the bags were opened after 60 days of silage at room temperature. 【Results】 The contents of YF, DM and WSC in milk stage were significantly higher than those at heading stage (P< 0.05), and CP content was significantly lower than that at the heading stage (P< 0.05). There were significant differences in NDF and ADF contents in all cultivars except for NDF content of Qingyin No.1 (P< 0.05). The pH value of Qingyin 1, Longyan 2 and Longyan 3 were significantly different in two harvest periods (P< 0.05). Meanwhile, there were significant differences in the content of LA in Souris, Longyan 3 and Charm period (P< 0.05), and there were significant differences in NH₃- N content (P< 0.05). The DM content at milk stage was significantly higher than that at the heading stage (P< 0.05), and the contents of NDF, ADF and CP at the heading stage were significantly higher than those at milk stage (P< 0.05). After 60 days of silage fermentation, the contents of DM, NDF, ADF and WSC decreased significantly (P< 0.05), CP content increased significantly (P< 0.05), pH value decreased significantly (P< 0.05), and LA, AA, PA contents increased significantly (P< 0.05). 【Conclusion】 In this study, the quality of all kinds of oat silage at milk stage was better than that at the heading stage. Among the five varieties, the fresh grass yield, nutritional quality and silage quality of Souris were the best whether harvested at the heading stage or milk stage, so it is strongly suggested that planting this variety at milk stage was the main mode of local oat silage production.