With one year and a half birch saplings as experimental materials,we investigated the effects of water,nitrogen and methyl jasmonate(MeJA) treatment on the accumulation of triterpenes and the accumulated regulation of triterpenes in birch.The results showed that,total triterpene is mainly distributed in stem bark and leaf in birch sapling,the average content is 71.94 mg·g^-1 and 81.60 mg·g^-1 respectively,and the lowest in root bark,which is 25.45 mg·g^-1.The accumulated peak of total triterpene in leaf is June and July;But accumulated peaks of total triterpene in stem bark and root bark are August and July,respectively.Moderate and severe drought stress had significantly contributed to the accumulation of total triterpene in leaf in the early stage of drought stress,which are 1.24 and 1.27 times of the control.The accumulation of total triterpene for water stress in stem bark is significantly higher than at of control in July.Water stress has not conducived to total triterpene accumulation of the stem bark in other months.In addition,drought stress is adverse to triterpene accumulation in the root bark.Nitrogen treatment in early stage (June) is not conducive to triterpenoids accumulation in the leaves and root bark,but has remarkably contributed to the triterpenoids accumulation in late stage (July-October).However,the nitrogen treatment has contributed to the triterpenoids accumulation in the stem bark in early stage (June-July).MeJA spraying has promoted the triterpenes accumulation in the leaf and root bark.In the accumulating peak stage,with 1.52 and 1.42 times of the control.Light drought,nitrogen fertilizer both contribute to height growth and biomass accumulation of birch saplings,but MeJA treatment is disadvantage on the whole plant biomass accumulation.