Abstract: Since Eucalyptus maideni was introduced from Australia in early 1950s,it has developed rapidly in Yunnan Province.However,most of the trees were scattered everywhere so that they couldn't be used as commercial timber.Whether it can be planted in low mountainous area on largescale and how its economical efficiency can be have always been the center of people's concem.By adapting the new increased pure profit method,time-factor analysing method and extention effect method,the author takes the research achievement "Exemplary planting Experiment on high-yielding Eucalyptus" for example,predicts and analyses its economical efficiency-the output value of per mu high-yielding Eucalyptus is 402.06 yuan,175.66 yuan higher than the common Eucalyptus can cam 515 yuan.From 1989 to 1995,the predicted profit will hit 30,570,000 yuan.The author concludes that the high-yielding Eucalyptus forest can be developed and planted in low mountain area on largescale and earn obvious economical efficiency.