The invention discloses a method for preserving Brassica oleracea L.var.italicaPlanch. The method comprises the steps of material selection, precooling, rinsing, fresh-cutting, antibacterial coating, sorting, air-conditioning refrigeration and the like, wherein the step of rinsing is that CaCl2 ice water with the concentration of 1-3% is used to rinse for 5-10 min; the step of antibacterial coating is that the fresh-cut Brassica oleracea L.var.italicaPlanch cuts are soaked in natto filtrate with the concentration of 0.1-0.5% for 10 seconds; the framed Brassica oleracea L.var.italicaPlanch is placed in an air-conditioning warehouse for refrigeration, wherein the air-conditioning warehouse is provided with CO2, O2 and N2 and has the humidity of 80-90%; volume percentages of CO2, O2 and N2 are as follows: 1-9% of CO2, 9-1% of O2 and 90% of N2. The method provided by the invention is based on quality characteristics of Brassica oleracea L.var.italicaPlanch, and is reasonable in process design, simple and practical in technical solution, and low in cost, thereby being suitable for industrial production. The preservation period of Brassica oleracea L.var.italicaPlanch is more than 90 days after the rinsing, antibacterial coating, air-conditioning refrigeration and other comprehensive matching preservation technologies are implemented.