The chromosomic meiotic behavior of pollen mother cells (PMCs) of the hybrid progenies from Triticum timopheevi×Avena fatua L.var.glabrata Pat was researched by general cytology and genomic in situ hybridization (GISH) in the present study.The results showed that the PMCs meiotic index of the F₃ line was 87.46,indicating some genetic instability.4 pairs of red hybridization signals were found in the PMCs at the metaphase I by GISH analysis,and there was a red signal in each dissociative univalent.Some lagging chromosome,chromosome bridges and micronuclei were discovered at the anaphase Ⅰ,anaphase Ⅱ and telophase Ⅱ,with the percentage of 10.58%,1.92% and 12.36%,respectively.Wheat homologues or homoeologues normally pairing was interfered by the wild oat chromatin might lead to these abnormal phenomena.