Preserve natural forest is primarily forest protection. Natural forests have a stronger stabilities than artificial forests. The species and structure of artificial forest is single, its ecological function and biodiversity were lower than those of natural forest. The surface material, shrubs and other vegetation of natural forest formed a stable and perfect natural ecosystem, to deal with possible extreme weather, natural disasters .Also ,drought season can easily cause forest fire ,especially artificial forests. Which can lead to great damage on for financial and ecology. We Chinese start "natural forest protection project" which covered 18 provinces for 17 years up till now.