The invention discloses a pot cover which comprises a pot cover body, a sterilizing module, a control device and a shielding module, wherein the sterilizing module comprises an ultraviolet LED lamp, and a light guide pillar is arranged at the light emitting side of the ultraviolet LED light. The pot cover has the advantages that the sterilizing effect is good, and the ultraviolet light is long in service life. The invention also discloses a pot which comprises a pot body and the pot cover covering the pot body. The pot has the advantages that the sterilizing effect is good, and the ultraviolet light is long in service life.The invention further discloses a pot additionally provided with a heat preservation module electrically connected with the control device, wherein the control device is arranged on the pot body and/or the pot cover body and is connected with the heat preservation module or a temperature sensor. The pot has the advantages that the sterilizing effect is good, and the ultraviolet light is long in service life. The invention further discloses a preservation method for food in the pot, which comprises the steps: during cooking, a shielding part covers the pot, a light passage is sealed; and after cooking is ended, preset sterilizing temperature is reached, the shielding part is opened, the light passage is opened, the ultraviolet LED light is turned on, and ultraviolet light is transmitted via the light guide pillar and penetrates through the light emitting side of the sterling module to irradiate food in the pot. The method has the advantages that the operation is simple and convenient, the sterilizing effect is good, and the preservation effect is good.