Abstract: Abstract: As the main reason of land use changes, human activities will result in not only economic but also eco-environmental and social effects. Currently, the protection of land resources has been a hot issue due to the prominent contradiction between human and land. The assessment of land use health can diagnose the damage and degradation degree caused by human activities, which is the foundation of sustainable land utilization. In Karst region which is one of the most ecologically fragile areas, land restoration is extremely difficult once the eco-environment is damaged. In order to protect the land use system and diagnose the health status in Karst region, this research proposed a triangle model to assess the health status of land use system and its changing trend in Guiyang city, which is a typical Karst region in China. The study period was from 2005 to 2012, and the data used in this paper were collected from Guiyang Statistical Yearbook (from 2005 to 2013), Guiyang Land Use Update Survey Table (from 2005 to 2012), Guiyang Water Resources Official Reports (from 2005 to 2013), Guiyang Environment Official Reports (from 2005 to 2013) and China Environmental Statistics Yearbook (from 2005 to 2013). Firstly, the research defined structured index, functional index and beneficial index to reflect the health status of land use system. To match the requirement of establishing a triangle model, the first 2 indices had to be converted to non-structured index and non-functional index respectively, to form a relationship of trading off and taking turns among these 3 indices. Then, a triangle graphic could be drawn to illustrate the health status of land use system and its changing trend during the 8 years according to the 3 indices above. The result showed that the non-structured index totally had a declined trend from 2005 to 2012 except 2007, the non-functional index had a fluctuated trend and the beneficial index had an uptrend from 2005 to 2012. The health status of land use system in Guiyang city was sick in 2005, and it changed to a sub-health status between 2006 and 2008, then to an elementary health status in 2009, which was probably resulted from a more reasonable layout and utilization with the implementation of the new comprehensive land use planning. After that, as Guiyang proposed a new development route which emphasized a double-win situation between economy development and eco-environment protection, the non-structured index and the non-functional index further declined while the beneficial index continued to increase, and the system came to a status of intermediate health from 2010 to 2012. For the changing trend of land use health, Guiyang had an obvious uptrend from 2005 to 2012, and it was predicted to get to an advanced health status in the future. In the end, several suggestions were proposed to protect land use health including optimizing the land resource distribution, raising the basic security level of economic construction, making full use of land to develop green eco-economics with the science advantage and using the advanced technology of information to build pre-warning system of health status for land use system.