Abstract: In this study, pollen grains of 9 species of Lilium were examined all under LM and SEM. The pollen characters and gross morphology, and their evolutionary trend in Lilium are discussed. Combined the view of the pioneer with our studies, some conclusions are drawn as follows:1. The pollen grains are generally elliptic and monocolpate(distal).2.An evolutionary line of exine ornamentation in Liliurn is as follows; ornate—→two-rows-retipilate—→one and two-rows-retipilate—→one-row-retipilate.3. For the first time one-row-retipilate and two-rows-retipilate are found in the same grain, and key to species of Lilium based on the pollen morphology is first made.