It is a very hard work to measure the length and diameter of roots in studies of physiology, genetic breeding, crop cultivation and so on. On the basis of analyzing the characteristics of roots, a method was developed for measurement of root length and diameter by applying geographic information techniques using personal computer and scanner. The result measured using this method was compared with that obtained using grid-counting method and direct-measuring method. It was found that there were close relationships between GIS-measuring method and the other traditional methods, and measurement precision was enough. The procedure is simple with quick measurement speed.