Abstract: This work on Brandt 's vole, Microtus brandti, was carried out at Amugulcng, Xinbarhuznoqi, Inner Mongolia from April to October in 1985．The data were collected mainly by mark and release trapping．A total of 2786 individuals were marked．The analysing results were as follows： 1.There are apparent seasonal changes in population age composition. In early spring most in dividuals the population are overwintering adults, weighting 21- 30 grams． 2.The average daily growth rate of the young vole decreased with time from spring to autumn，its regression equation is LgY=0.9312-0.8317LgX. 3. The seasonal migration of the vole is apparent．The ditch is its optimal habitat．The voles emigrate from the ditch outwards after reproduction in spring and immigrated backwards in autumn．

Key words: Brandt‘s vole, Microtus brandti, Population age composition, Growth rate, Seasonal migration。

摘要： 1985年5-l0月用标志重捕法对布氏田鼠(Microtus brandti)的种群年龄组成、幼鼠生长率和季节迁移等进行研究，共标志2786只，重捕576只,822只次。发现布氏田鼠种群的年龄组成有较明显的季节变化。其幼鼠体重的日平均生长率随年龄增加而减慢。布氏田鼠还有季节迁移现象。

关键词: 布氏田鼠, 种群年龄组成, 生长率, 季节迁移。