Abstract: The management and improvement of low-value forests is an important issue of forestry in China. This paper put forward a new thought of early diagnosis for low-value forest. By applying this method,the forest growth trend before the explosion of the state of low-value forest was diagnosed according to the formation rule of low-value forest,and so,managers could adopt corresponding management measures in time. Taking a case study of Chinese pine plantations in western Liaoning Province,the early diagnosis of low-value forest was studied,and set up early diagnosis techniques of ecological factor approach based on single factor experiment and discriminant analysis: 1) following discriminant indices were selected: soil thickness (X₁),organic matter (X₂),soil nitrogen content (X₃),soil water content (X₄),and soil microbic quantity (X₅);2)discriminant function could be expressed as: Y=1.596X₁- 0.51 X₂-3.196X₃+1.622X₄+1.898X₅ ;3)early diagnosis of low-value forest was carried out by discriminant function and the value of each discriminant index. For early diagnosis of low-value forest,this paper is a pilot study. It is suggested that the forming mechanism of low-value forest and their related study should be strengthened.