Abstract: Return to trueness means getting rid of exterior trimming and returning to reality of a thing. On the different levels of forest aesthetics, the concepts of trueness are different. From the viewpoint of forest landscape, trueness is represented by the outwardness of aesthetics objects, which means the arousing of peoples emotion by forest landscape. From the viewpoint of forest image, trueness is represented by peoples sincere emotion, which means the fusion of peoples emotion and forest landscape. From the viewpoint of forest artistic conception, trueness is represented by peoples sincere disposition and inspiration, which means the unity of human and nature. Trueness is not only the logic origination of forest aesthetics, but also run through the whole process of forest aesthetics, and embodies the form, content and spirit of forest aesthetics.