Abstract: Using degenerate oligonucleotide primers corresponding to the conserved domains of the Ty1-copia retrotransposon reverse transcriptase, 23 Ty1-copia retrotransposons reverse transcriptase sequences were isolated by polymerase chain reaction (PCR) from the genome of Avena nuda L., and characterization, phylogeny and transcriptional activities of these sequences were carried out. Results showed that the retrotransposons had high heterogeneity, with 45%-98% identity between sequences. The DNA sequences displayed mutations, including insertions, frameshifts, and stop codons, but the frequencies were not high. Phylogenetic analysis showed that the Ty1-copia retrotransposons of oats were mainly transmitted vertically during evolution. Five Ty1-copia retrotransposons with transcriptional activity were found by searching the oat gene expression database.