Abstract: High-temperature superconducting cables are able to transmit high current with low losses, and validated in a number of demonstrations. Commonly the cables are cooled by liquid nitrogen, which have the advantages of cheap coolant, easy operation and easy maintenance. While in some scenario as on mobile platform, volatile liquid may not be allowed or hard to replenish timely. At this point, conduction cooling becomes a feasible solution. Compared to liquid immersion, efficiency of conduction cooling is lower because it depends on solid state heat exchange. Thus, heat loads are critical and necessary to be investigated in cable design and development. Quantitative results and matches with the cooling power are needed for safe and stable operation. There are three main sources of heat loads: the heating of cable body, the heating by lead resistance plus its heat conduction, and the heat transfer into the wall of the low temperature chamber. Utilizing the prototype cable and its test platform in Xidian University, typical results of heat loads and cooling power were obtained, preliminary parameters to calculate heat loads were proposed, and the operation and improvement experiences gathered here could be valuable in the future development of practical cables.