In order to define suitable shading way of ginseng, the photosynthetic rate and root absorptivity of ginseng were measured bY using ¹⁴C and ³²P isotops as tracers under various light intensity. The result showed that saturation light intensity of ginseng was 20Klx or 25％ LTR （light transparent rate）. When ginseng grown under light intensity more than 20 Klx, photorsynthetie rate lowered, color of leaves changed yellowish, as’ginseng grown under 30％ LTR, that root of ginseng absorbed the a mount of ³²p was lower than under 10％ LTR. Therefore suitable shading way of ginseng should extend duration of sunshine, the greatest light intensity should not be more than 25％.