The work aims to study the effect of negative ion treatment time on the storage quality of spinach (Spinacia oleracea L.). In this experiment, a negative ion generator was used to produce negative ions in a confined space for the pretreatment of spinach before storage. The effects of four treatment times (0 min, 30 min, 60 min and 90 min) on the storage quality of spinach were investigate by measuring the total viable count, respiration rate, weight loss rate, color difference (ΔE), malondialdehyde and total phenol content of spinach during storage. Negative ion treatment could inhibit the growth of microorganisms on the surface of spinach, reduce the damage caused by microorganisms on the organism, delay its oxidative aging, reduce the respiration rate of spinach, reduce the consumption of nutrients and the decomposition of chlorophyll, and maintain a lower weight loss. With the increase of negative ion treatment time, the quality protection effect of spinach during storage was more obvious. Negative ion pretreatment for 90 minutes had the best effect on the storage quality maintenance of spinach. It could be visualized in the change of the appearance of spinach and the maintenance of color and luster. An appropriate treatment time of negative ions can effectively prolong the shelf life of spinach, which provides an important basis for the application of negative ion pretreatment in the preservation of fruits and vegetables.