Abstract: The effect of light intensities on the chemical constituents of the tuber of Pinellia ternata(Thunb.) Breit.(ovate leaf) was studied with the plants which were grown under different light intensities.When the sprouts wilted in autumn,the tubers were collected and the chemical constituents of it were measured.Results showed,there are higher alkaloids,guanosine and proteins contents with full sunlight treatment or without shading treatment.The tuber weights were bigger with 55% shading treatment.And the contents of reducing sugar and soluble sugar were higher.With 80% shading treatment,The contents of the chemical constituents were significantly influnced by different shading treatments.Full sunlight treatment is in favor of alkaloid,guanosine and protein accumulation.Reducing sugar and soluble sugar increase benefited from 80% shading treatment.And 55% shading treatment is conducive to the Pinellia ternata(Thunb.) Breit growth,but its chemical composition contents were less than full sunlight.