Abstract: According to the data source used, the major methods globally used to estimate forest above-ground biomass were introduced in this paper. The methods can be categorized into forest inventory data based method and remote sensing based method. Based on previous studies conducted in China and abroad, we summarized the characteristics and the deficiencies of these two kinds of methods and then preliminarily explored the synergetic method in estimating forest aboveground biomass using multi-source data. In accordance with the deficiencies of estimation methods, some discussions about the scale, parameterization and validation of the models were given and some work concerning the estimation of forest aboveground biomass in the future was stressed.