Abstract: We studied meiosis process and tepetum changes of OT hybrid lily cultivars ‘Cocossa’ using aceto-carmine dyeing method combined with grilled slices paraffin sections. When the bud grew to 2.5-4.5 cm, the pollen mother cell was in the period meiosis. There were some abnormalities appearances of meiosis:chromosome ring appeared in metaphase Ⅰ, chromosome bridges and lagging chromosomes ppeared in anaphaseⅠ, unequal division and micronuclei appeared in telophaseⅠand Ⅱ, it could also be observed 2 split-phase in the same plant, the same flower bud and even the same anther, that showed meiosis had not synchronized. During the telophaseⅡ and mononuclear pollen period, the tapetum delayed degradation, which led to multinuclear pollen, abnormal pollen and microspore infertility. The meiotic abnormalities and abnormal tapetum degradation could common cause the microspore abortion.