This study employed four approaches for estimating carbon storage in HWP, including the IPCC Default Ap-proach, the Stock-Change Approach, the Production Approach, and the Atmospheric-flow Approach, according to the four criteria being feasibility of approach, accuracy of approach, the relevance to the reporting needs of United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol (KP), and relevance to national policies. This study is to help policy-makers choose an approach to be used in National Greenhouse Gas Inventories under the IPCC Guidelines before it is mandatory to report the HWP for the Parties under the KP. We found that at the national level, the four approaches gave significantly different results and had different political, social-economic and environ-mental implications. Indeed, an internationally agreed approach was crucial to avoid double accounting or omission. However, all the approaches have both advantages and disadvantages concerning the achievement of political goals, while none of them is perfect. Then, this paper makes no policy recommendations as it is extremely complicated to take the direct and indirect incentives, as well as different scenarios assumed and conflicting policy goals into consideration.