Abstract: According to the data of 6th national forest inventory, we analyzed the forest resource size distribution by timberland area and forest volume. The loglog plots showed that the forest resource size of China was inconformity with Zipf’s law, and it was a feasible way to study the ranking structure of forest resource quantitatively by Zipf’s law. Through the research on timberland area, the plot shows that 26 of 31 units were located in the scaleless band and the Zipf dimension could be known by the fitting equation. The conclusion was that the timberland area size distribution had a fine ordering structure that can be drawn. However, the loglog plot of volume size in China demonstrated that the distribution had the character of double fractal, which means there were two scaleless bands on the plot. Also it could be deemed as that there exist two subsystems in volume size system of China. And the character of double fractal illustrated that the ordering structure of volume size in China need to be enhanced. Scaleless band Ⅰ of the volume size system included five units and the Zipf dimension, while 20 units located in scaleless band Ⅱ and the Zipf dimension. The above results interpret that the structural difference of scaleless band Ⅰ is much less than that in scaleless band Ⅱ. Perhaps the reason was that the effect of afforestation was on the primary stage. We could get instant outcome on the ordering structure of timberland area compared with the forest volume. It also reminds us of that enhancing the quality of forest is a longterm mission.