Abstract:In accordance with the data of annual volume increments of 99 trees, 220 year-old Korean pine, the age groups of natural Korean pine forests are studied and analysed by the method of category assembling. The results are as follows: young forests, 1—80 years;middle age forests, 81—140 years; near mature forests, 141—160 years; mature forests, 161—200 years;over mature forests, over 201 years.Through variance analysis and multi-layered comparison, it shows that the differences of annual volume increments among the age groups are significant, and it is demonstrated that the abormentioned standard is scientific and reasonable. Perhaps this standard is better than that in the"some technical rules of investigating forest resources" issued by the Ministry of Forestry of China in 1982.