The Contents of nitrate, nitrite and Vitamin C Were determined at different growth stages in three Vegetables: Brassiea Pekinensis Vat dissoluta, Spinacia oleracera and Brassica chinensis Var. tai-tsai. The content change of nitrate showed a curve of tape N, nitrite and Vitamin C showed tape M. These informations would give a reference to determine the appropriate period for harvesting and eating.