Abstract: 1116 mandarin voles (515 male，601 female)，were trapped in the farmland and orchardsof Lingbao and Lushi in the western Henarr province，from Feb． 1991 to Apr．1992．
Based on the values of the body weights excluding viscera，reproductive conditions and the color of the fur，we divided the voles into five age groups with the frequency distribution of total body weights excluding viscera(TBWEV)： I．Juvenile，in an immature stage and TBWEV≤11．5 g I I．Subaduh，alittle part of this group are in a mature stageand TBWEV > 11．5 g and≤ 20．5 g}II． Adult I，all the voles are in a maturestage and TBWEV~ 20．5 g and≤ 26．0 g；N．Adult I，in a mature stage and TBWEV>2 6．0g and≤30-5 g}V．Old，TBWEV >30．5 g．
T- test on the age groups divided by the body weight，the body length，the greatestlengthof skull and Zygomatic width wele not all more significant．It showed the trustworthiness of TBW EV．There was seasonal fluctuation in the population age composition，based upon the reproductive peaks throughout the year．

Key words: Mandarin vole (Microtus mandarlnus), Population age structure, Age determination, Body weight exciuding viscera

摘要： 1991年2月至1992年4月，在河南省灵宝市、卢氏县捕获棕色田鼠1116只(雄515，雌601)，应用胴体重作指标，参考繁殖状况及毛色，将种群划分为5个年龄组： I．幼体组，≤11．5 g；Ⅱ．亚成体组，11.6-20.5,Ⅲ成体Ⅰ组，20.6-26.0g;Ⅳ.成体Ⅱ组，26.1-30.5g;Ⅴ.老体组，＞30.6g。对比体重、体长 及头骨量度，胴体重法较能客观反映年龄状况。随季节变化，春季I、Ⅱ组占优势，夏季Ⅱ，Ⅲ组占优势，秋季、冬季V组数量增加，而其它各组的数量比较均匀。

关键词: 棕色田鼠, 种群年龄结构, 胴体重