Based on the field investigation, cytology and palynology research and the molecular systematics, the revision of the genus Yulania was carried.144 wild Yulania populations from 14 provinces in China were investigated and 959 specimens with more than 3,000 copies, which are belonging to 20 taxa, were collected; 387 accessions of DNA materials, such as leaves, petals, were collected; the pollens of 123 individuals were used for SEM studying and crossbreeding work; the graftwoods of 487 individuals were sampled and 164 clones were successfully grafted in more than 1000 stocks, which were used for the sampling of experimental taxonomy, cytology,anatomy and molecular biology research; 6702 herbarium specimens of Magnoliaceae species in 16 research units,mainly belonging to 16 taxa of Yulania, were studied,pollen exine ornamentation of 12 Yulania species were studied by scanning electron microscopy; the chromosome number of more than 10 taxa were counted, such as Y.sinostellata, Y.cylindrica, Y.zenii and so on; chromosome meiotic behavior of pollen mother cells of 60 different materials were observed, which belong to 18 taxa and their interspecific hybrids.