Located in the upper reaches of the Yangtze River and the Zhujiang River, Guizhou Province is one of the provinces carrying out the National Natural Forest Conservation Project It is also one of the major gene pool areas and one of the famous producing areas of medicinal materials in China The development and conservation of forest resources is not only significant for protecting environment and biological diversity but also important to the economic development of Guizhou and even the middle and lower reaches of the Yangtze River and the Zhujiang River According to forest data collected in 1979, 1984, 1990, 1995, and 2000 by the Institute of Forestry Survey and Design of Guizhou Province, this paper provides detailed information about the dynamic changes of forest resources and concisely explains the factors arousing these changes In general, Guizhou's forest resources decreased rapidly from the late 1970s to the late 1980s; but since 1990, they have steadily increased (1)The forestry land keeps almost unchanged since 1984; the major types of forests expanded considerably, especially the protective forest, economic forest and specific forest; timber forest increased with some fluctuation, while sparse forest and non forest land decreased (2) The growing stock of living forests has had a trend of increase since 1984; the growing stock of major types of forests decreased from 1979 to 1990, but began to increase thereafter (3) The area and growing stock of planted forests increased rapidly; natural forests also showed a trend of expanding, and their growing stock began to rise after 1990 (4) Young age forests grew quickly both in area and in growing stock; mid age and over mature forests showed a trend of decreasing in area and growing stock from 1979-1990 but a trend of increasing since 1990 The percentage of young age forests decreased, while that of mid age and mature and over mature forests increased (5) As for the composition of forest resources, the proportion of timber and fuel forests has lowered, while that of shelter, specific and economic forests increased (6)Since 1990, thanks to the implementation of several ecological and sustainable development projects in Guizhou, its forest resources have grown enormously, and the ecology and environment greatly improved