Some important problems on natural forest protection are demonstrated in this paper. From the point of view of forest eco_environmental value, it has been illustrated that the eco_environmental value of the natural forest is far more than its economical value, and more than eco_environmental value of the artificial forest. It has been put forward that establishing the compensation mechanism of the forest eco_environmental value is to gurantee the implement of natural forest protection engineering, and the forest eco_environmental quality assessment is an impontant foundation for carrying out natural forest protction engineering. The indicator system framework and the method of the potential risk evaluation for water loss and soil erosion in zone have also been constructed. Finally, this article has put forward three factors to determine the protection object of natural forest, namely, ecological fragility, the purpose of natural forest protection as well as social and economical factors.