Snow melting system in road is a device which prevents being frozen for safety. If the snow melting system with piping is used, the economical benefit is growed and the geothermal unbalance for years is able to be solved, also. Because the snow melting system with piping is different with the electric snow melting system in design aspects, it requires additional considerations such as kinds of pipe, heat medium and flowrate etc. In this paper, for predicting the heat dissipation to air side of the snow melting system of piping, CFD simulation are performed. And the variation of road surface temperature along time for thickness and kinds of the pavement is investigated. Flowrate of heat medium is not big effect on heat dissipation in same diameter of pipe. As the diameter is increased from 25A to 32A, the amount of heat dissipation is increased from 149 to 215 W/m². If the pipe spacing is increased or reduced by 16.7 % based on 150 mm, the amount of dissipation is increased or decreased by 20% or 18%. It can be seen that the top layer pavement largely affects on the time when the road surface temperature reaches 0℃.