Abstract: The meiosis stages of megaspores and microspores of two white poplars (Populus tomentosa × P. bolleana and P. alba × P. glandulosa) and their relationships were studied. The results indicate that the meiosis stages of megaspores of these two white poplars are different. When cultured in water in the greenhouse for 84 h,the meiosis stages of the megaspores of Populus tomentosa × P. bolleana developed into leptotene and the meiosis stages lasted very long. Those of P. alba ×P. glandulosa split into leptotene when cultured in water for 140 h and the meiosis stages were shorter. When the flower-branches cultured in water for 6-7 d, their meiosis stages of megaspores developed into pachytene. In the process of the experiment, the branches with buds of white poplar were collected and cultured under the same conditions, their meiosis stages of megaspores and microspores were closely related with development.When the meiosis of microspore mother cells developed into tetrads, that of megaspore mother cells just entered leptotene. When the meiosis of megaspore mother cell developed into pachytene, most of microspores developed into mononuclear that its nucleus had moved to one side of the cell. According to the relationship of female and male gametes, the meiosis stages of megaspore could be discriminated timely through observing the meiosis of microspores under the same conditions.