Abstract: Consequences from the experiments of the creep of the solid wood beam of poplar in different moisture conditions stressed that, unlike the behavior of and result from the creep in constant humidity which was affected only by the uniform moisture content, the principle dynamics of the creep in varying humidity was the moisture gradient which was changing. It was pointed out that the creep “recovery” during the adsorption was the negative deflection in truth. Meanwhile it was found out that most of the deflection of the creep in varying humidity happened in the initial varying stage when the moisture gradient was maximum and sharply changing; and the creep deflection during adsorption was not always negative. Sufficient attention should be paid by the designers, manufacturers, users and code makers for solid wood beam to the behavior and result of the creep in varying humidity and its sound difference from that in constant humidity.