Agave americana L., a drought\|tolerant plant with high\|value of medicinal use, was introduced to the arid valley of the upper reaches of the Mingjiang River in 2000. In order to evaluate it role in vegetation restoration and determine the optimal adaptation range in the area, plant traits such as height, crown diameter, leaf number and sprouts were measured along altitude ranging from 1400m to 2000 m for the purposes of assessing growth conditions and estimating above\| and below\|ground biomass. It was found that 1400-1500m above sea level is the optimal growing area of Agave americana. The mean height, crown diameter, leaf number and sprouts in this altitude were up to 62.7 cm, 0.385 m2, 22 blades, 27 buds, which are larger than those in other altitudes. The upper limit of Agave americana is 1800 m and it can only survive but not reproduce above this altitudinal limit. The biomass is significantly correlated with height, crown diameter and leaf number, which can be used for estimating above\| and below\|ground biomass through established allometric biomass equation.