Objective： To explore the effect of cholesterol treatment on the preservation of postharvest pak choy （Brassica chinensis L）. Method： Postharvest detached pak choy was completely immersed in 0.1 mmol/L cholesterol solution for 2 h and stored at 2 ℃. Quality related parameters of pak choy were determined during the storage. Result： Exogenous cholesterol treatment could significantly retard the decline of ascorbic acid （AsA）， and the increase of weight loss rate， nitrites and malondialdehyde（MDA）. Cholesterol also contributed to the preservation of soluble protein， chlorophyll and soluble solids content（SSC）. Cholesterol treatment could effectively enhance the activities of superoxide dismutase（SOD） and ascorbic acid peroxidase （APX）， as well as catalase （CAT） and glutathione reductase （GR）. However， little effect was found on peroxidase （POD）. Cholesterol could stably promote the activities of APX and GR enzymes， and APX， AsA and GR were positively correlated with chlorophyll. Conclusion： Cholesterol treatment was beneficial to maintain the quality of postharvest pak choy， sustain the content of reduced AsA， and keep pak choy green.