New enhancement mechanism of radiative heat transfer based on the multi-band feature of radiative gas is proposed. A theory taking into account the multi-band feature of radiative gas and continuous solid radiation from surfaces is developed. Calculation is carried out for the system of high temperature CO₂, H₂O and combustion gases surrounded by two infinite parallel heat absorbing surfaces. Enhancement of nearly 55% for CO₂, and 35% for H₂O and combustion gases is attained by putting a solid plate between two parallel heat absorbing surfaces. This enhancement mechanism is due to two factors. First, the frequency transformation of radiative energy from gas band radiation to continuous solid radiation, and second, the non-linear dependence of effective band width on optical beam length. The influence of gas temperature, heat absorbing surface temperature and distance between the surfaces on the enhancement performance is made clear. It is also made clear that the radiative heat transfer is enhanced by increasing the emissivity of the solid surface.