Betula microphylla is one kind of typical desert and mountain plants trees that distribute only in Xinjiang in China.Inflorescence phenological phase,growth rhythm and set seeds were studied to comprehensively understanding the inflorescence growth phenology and and ecological adaptation of B.microphylla.The results are as follows:The staminate inflorescence of B.microphylla is the two year reproductive organs,whose phenological phase contains 154 days of vegetative growth,158 days of dormancy and 33 days of flowering growth.The pistillate inflorescence and infructescence are annual reproductive organs,whose phenological phase contains inflorescence growing stage of 24 days and infructescence growing stage of 90 days.In spite of the difference of growth cycle between the staminate and pistillate inflorescence,the staminate and pistillate bud burst time appear same in the late in April,exhibiting a centralized pollination mode and result in more seed number and seed rate and higher seed dynamic.As it mentioned above,in a word,B.microphylla can successfully completion of the process of sexual reproduction in the extreme desert environment.