Abstract: 【Objective】 To study the effects of different sowing dates on the growth, development and quality of overwintering spinach in northern Xinjiang. 【Method】 Two spinach varieties , Green Crown 369 and the American Big Leaf , were used as testing materials. According to the change trend of temperature, they were sown on August 15, August 25, September 15, 2018, and the growth index, quality index, yield, bolting time and other related indexes were measured in the spring of the following year. 【Results】 Under the condition of open field cultivation, the two spinach varieties could survive the winter safely at three different sowing dates. The oxalic acid content of them decreased with the delay of sowing dates, bolting time was delayed in the next spring, the number of effective leaves was proportional to the increase of effective yield, and the number of effective leaves and effective yield of the two spinach varieties were the lowest after overwintering as early as August 15. 【Conclusion】 The effects of different sowing dates on some quality indexes and yields of overwintering spinach in open field are obvious. In order to achieve the purpose of high efficiency and high yield cultivation, according to the local temperature conditions, it is suggested that it is appropriate to sow when the average temperature is reduced to 15-20℃ in northern Xinjiang, generally after August 25.