The present invention relates to the field of take-out food cases, more particularly to a take-out food case for keeping food fresh. The principle is as follows. The temperature information of the heat insulation portion is detected and fed back to the temperature controller by the thermocouple probe. When the detected temperature is lower than the minimum temperature preset by the temperature controller, carbon fiber heating pipes are controlled to heat the food by the temperature controller. When the temperature inside the heat insulation portion reaches to the maximum temperature preset by the temperature controller, carbon fiber heating pipes are controlled to stop heating by means of the temperature controller. When the take-out food case for keeping food fresh is not in use, ultraviolet sterilizing lamps are controlled to perform regular sterilization for the take-out food case by means of the timer.