The heat energy budget was analyzed over a reclaimed land covered with reeds around the coastal wetland. The mud consists of fine particles characterized by small gap and the heat transfer is obstructed by moisture in the gaps. The relationship between net radiation and soil heat flux showed a counterclockwise hysteresis cycle, which refers to a time lag behind the maximal soil heat fluxes. The soil heat flux decreased in about 75% under the vegetation canopy than in the bare soil. The remained heat was stored in the canopy layer in the daytime, and therefore the air temperature in the canopy layer was higher than that over the reed canopy. During the nighttime the air over the reed canopy was warmer than the canopy layer. The vegetation canopy controlled the interaction of the heat between the air and the soil so that the amplitude of daily temperature variation was reduced.