Abstract: The paper first discusses the function of forestry in the setting of the guidelines of constructing a harmonious society. The two key aspects of a harmonious society are the harmony among people and the harmony between people and nature. The paper holds that the harmony between people and nature dominates in the construction of a harmonious society. Therefore, the guideline of constructing a harmonious society must begin with people_nature harmony and use scientific means and measures of natural science, in which ecology is the most suitable principle to be used for constructing such a harmonious society. Forestry is an important sector in practicing ecological principles and has a basic function in reserving nature. It plays a fundamental role in constructing a harmonious society and, through decades of development, China??s forestry has accumulated many valuable data and rich experience. The role of forestry in this respect will be more prominent and be of primary importance in constructing a harmonious society.