Rat liver ribosomal RNAs on surfaces of mica were imaged by atomic force microscope (AFM) under ambient condition. A number of images of 28S-5.8S、18S、5S rRNAs were obtained directly. The rRNAs were prepared by thawing the solution of low concentration of ribosomes repeatedly to crumble the ribosomes. The rRNAs were scattered on surface of mica very well. The rRNAs prepared by this method were always in three forms when they were scattered on surface of mica. The structures of the three forms of rRNAs were consistent with the established models by computer for 28S-5.8S、18S、5S rRNAs respectively. The result supports the models of the secondary structures of rRNAs considered by the thermodynamic principle. It is demonstrated that AFM could provide valuable three-dimensional information of rRNAs.