[in Chinese with English abstract: ] Group I introns in SSU (Small Subunit) rDNA of lichen forming fungi and their distribution modes were analyzed in this study. The data were obtained from eight species of the lichen genera Physcia and Phaeophyscia with some sequences retrieved from GenBank. Our result indicates that there are multiple group I introns insertion sites in SSU rDNA of lichen forming fungi, and their secondary structures gives the evidences of transposition when group I introns are in its nature states. Our result also demonstrates that group I introns are only suitable for the phylogenetic analysis at infraspecific levels. Key words: distribution mode of group I introns, secondary structure, small subunit rDNA, ITS sequence.