Abstract: Abstract：Biodiversity conservation is an essential part of delimitation and strictly execution of ecological protection red line. How to accurately identify the most important areas for biodiversity conservation is the key to delineate the red line for biodiversity protection scientifically. In this study, Qinling Mountains was selected as a case study example. According to the special richness patterns along the elevational gradient in Qinling Mountains, with the recognition results of the most important areas for biodiversity conservation in nature reserves, a scientific and reasonable biodiversity protection red line management plan in this area was put forward. The conclusion can be drawn as follows: first, it shows that revised NPP method improves the accuracy of identification of important areas of biodiversity conservation function, which can be applied to mountainous areas where species richness changes as medium peak type or monotonic incremental type with the elevational gradient in eastern-central China. Second, the red line area of ecological protection in Qinling Mountains is 24 688.33 km², accounting for 39.11% of the total area of Qinling mountainous area. Spatially, it can infer that the red line areas are concentrated in western Qinling Mountains, scattered among the eastern Qinling Mountains, and appears on a diminishing scale from south to the north; Third, forest ecosystem is an significant supporting system for the red line of biodiversity conservation in Qinling Mountains, accounting for 96.12% of the total area. In this study, the amendment of the delimitation method is reasonable and feasible, which improves the accuracy of identification of important areas of biodiversity conservation function. At the same time, the research results can be taken as an important reference to the Boundary optimization and Implementation of the red line for biodiversity protection.