By comparison to the amino acid sequence of OsAGO7 in rice with BLASTP tool, PpAGO7 gene was cloned from Physcomitrella patens; and the expression pattern was analyzed by realtime PCR. The full length sequence of PpAGO7 was 3 583 bp, containing a 3 363 bp open reading frame (ORF), which encoded a protein of 1 120 amino acids. Realtime PCR analysis showed that PpAGO7 gene was expressed throughout the whole life cycle of P. patens. The expression level of PpAGO7 gene in cormophyte period was higher than that in protonema period, and the expression level in the upper part of mimicry leaf was the highest. These results indicated that PpAGO7 gene may play an important role in the growth and development of mimicry leaf in cormophyte.