A total of 11 kinds of biomass models were adopted to estimate the biomass of single tree and its organs in young (7-year-old), middle-age (16-year-old), mature (28-year-old), and mixed-age Chinese fir plantations. There were totally 308 biomass models fitted. Among the 11 kinds of biomass models, power function models fitted best, followed by exponential models, and then polynomial models. Twenty-one optimal biomass models for individual organ and single tree were chosen, including 18 models for individual organ and 3 models for single tree. There were 7 optimal biomass models for the single tree in the mixed-age plantation, containing 6 for individual organ and 1 for single tree, and all in the form of power function. The optimal biomass models for the single tree in different age plantations had poor generality, but the ones for that in mixed-age plantation had a certain generality with high accuracy, which could be used for estimating the biomass of single tree in different age plantations. The optimal biomass models for single Chinese fir tree in Shaowu of Fujin Province were used to predict the single tree biomass in mature (28-year-old) Chinese fir plantation in Jiangxi Province, and it was found that the models based on a large sample of forest biomass had a relatively high accuracy, being able to be applied in large area, whereas the regional models with small sample were limited to small area.