Sand-laden wind structure and sand erosion-deposit budget over gravel bed under abundant and deficient sand supplies were studied in wind tunnel experiment. The sand-laden wind structure is a significant judge to distinguish sand-saturated structure from unsaturated one, indicating different erosion-deposit characters of gravel bed. The structure within 0~6 cm height mainly indicates the erosion-deposit characters of gravel bed, and that above 6 cm reflects the sand-transported condition by wind. Sand supply determines the saturation degree of sand-laden wind and whether the gravel bed is in erosion or in deposition. Given the same wind condition, the sand transporting rate of saturated sand stream is 2 to 8 times of that of unsaturated one. Sand deposition phenomena mainly happen in condition of saturated sand stream, and the deposited sand quantity increases sharply with the increase of wind speed. Whereas, processes of erosion and sand transportation occur in condition of unsaturated sand stream, and the stream structure within 0~2 cm height reflects the obvious sand-arresting function of gravel bed, and the largest sand-transporting rate appear within the height of 2~5 cm.