Based on national forest inventory data of Guangdong province, and selecting 176 sample plots dominated by Pinus massoniana, the biomass of the sample plots was estimated with different methods, which taking the keep sample stock volume as the independent variable and the sample plot biomass as the dependent variable. By comparing the calculation principle and process characteristics of these methods, the appropriate process was chosen to estimate the sample biomass. The results showed that the effect of continuous function for biomass expansion factor was poor, while that of the other methods was similar. For estimating the biomass of Pinus massoniana, the method of simultaneous equations with intercept was the best.