The method of combining electron microscope scanning analysis with image analysis is used to determine the contents of rare earth minerals and niobium minerals in ores. Before the determination, first of all, categories and the chemical compositions of these main minerals have to be examined thoibughly. The X-ray plane scanning of electron microscope is carried out to differentiate the elements according to the main elements association, for example Ge-P is monazite, Ce-Ti-Nb is eschynite, Huanghoite is Ce-Ba and the rest is bastnaesite. As to the Niobium minerals Nb-Fe is columbite, Nb-Mn and Nb-Ee-Mn is Maganocolumbite, Nb-Ti-Ce is eschynite, Nb-Ca is fersmite and pyrochlore (the further determination by microscope) Nb-Fe- Ti is ilmenorutile, Nb-Ce is brocenite and Na-Ti-Si is baotite. The X-ray plane scanning is carrying out on a special mode polished section on which all rare-earth minerals and niobium minerals are riched by special technologi- caI prossessing. Finally an image analysis instrument is used to prossess all image photos of the scanning and made them to be overlapping exactly and calculate the dimensions and proportions of each mineral respectively by computer.