In this article, TM image data covering nine sample areas of various landscape from the northern frigid temperate zone undulating plain to the southern subtropics hilly land one analysed and compared in many ways. The results indicate that the spectral information of TM image is essentially three to four demensional structure which physical meaning are match with Brightress, Greeness, Temperature and Humidity. In the seven TM bands, band 5 have the most ground information. There is the strong correlation between the three visible bands （band 1, 2, 3） and between the middle-infrared bands （band 5, 7）, which indicate that there is very much "repeatability" or "redundacy" information in these bands. Between band 6 especially band 4 and the other bands is there very low correlation, which is shown that the information of the two bands is with very large independence. Computing twenty kind of combinations indicate that the color images by one of the visible bands, one of the middle-infrared bands and band 4 is generally with the most ground information, in which the combination of band 4, 5 and 3 or band 4, 5 and 1 is the optimal combination.

信息结构;信息量;最佳波段组合