We studied the flower duration and reproductive allocation of Aconitum gymnandrum in different altitudinal populations on the Northeast of the Qinghai-Tibetan Plateau.Our results showed that:(1)The duration of individual flower in the high altitudinal population was remarkably longer than those in low altitudinal populations,and there was significant difference in flower duration between populations.(2)The biomass of flowers increased with plant size in the three populations.(3)The proportion of flowers in the total above ground biomass (reproductive allocation) increased along the altitude gradient.Consequently,we concluded that the importance of sexual reproduction in alpine environment was emphasized by the increased allocation of biomass to flowers,and prolonged floral longevity of A.gymnandrum along the altitude gradient suggested the mechanisms of compensation for the reduced pollinator availability and attraction to pollinators.