The work aims to improve the heat preservation performance of takeaway boxes to solve the problem of large heat loss in distribution of hot meals at low temperature. Carbon water-based electric heating ink with good heating performance and environmental protection was used in combination with screen printing technology to prepare a heating device and assemble it in a foamed polypropylene (EPP) takeaway box, so as to maintain constant temperature in the box. The saturation temperature of the heating device could reach 76.7 ℃ at 18 V. The temperature and power density were linear, and the slope was as high as 782.6 ℃.cm2/W. After the heating device was installed, the temperature in the thermostat could be maintained above 60 ℃ for a long time. After 1 hour of simulated distribution in the constant temperature takeaway box heated from the ambient temperature, the temperature of the hot food with an initial temperature of about 60 ℃ dropped by only 5 ℃. In the comparison test, hot water with an initial temperature of 60 ℃ was placed in the constant temperature takeaway box and the ordinary EPP takeaway box respectively. After 20 minutes, the heat preservation efficiency of the constant temperature takeaway box was 27.3% higher than that of the ordinary takeaway box. The heating device made of carbon water-based electric heating ink has low power consumption and high heating performance. Its application in constant temperature takeaway boxes improves the heat preservation effect and effectively reduces the temperature loss of takeaway.