Abstract: This paper discussed the spectrum structure and time profiles of greenness for wheat, corn, soybean and cotton in North-China according to spectral data observed in Yucheng, Shandong provinces in 1981 and 1982.It was proved that primary informations for interpreting the four crops containing in modes of greenness made up of reflectivity of visible region (0.4-0.7μm) and near-infrared region (0.8-1.1μm).The combination of any band in the visible region does not produce more informations for interpreting the four crops, nor does the combination of any band in infrared region.Graphic transformations and time profiles of the greenness which have unique features for four crops were depicted, and their roles in interpretation were shown.We presented three new models of greenness.G6, G7 and G3, with which we can approach cholorophyl contents for wheat, corn and soybean respectively.More informations for interpreting crops can be obtained when the models have been ingeniously combined and rationally used.Different time profiles of greenness will be got when division of band is different.The above mentined charati-cristics' should be considered in choosing optimum band for resource satellite of China.