Abstract:With cpSSR method, the variation of genetic diversity in temporal dimension of natural population of Pinus koraiensis in Liangshui national nature reserve was studied in this paper. Total 121 P. koraiensis samples aged from 101 to 420 years were grouped into 6 age classes. 5 polymorphic loci were obtained from 2 pairs of SSR primers and the percentage of SSR polymorphic loci was 71.43%.With the POPGENE analysis software, the genetic diversity index was calculated and the variation of genetic diversity was analyzed in every age class level. The results showed that the genetic diversity of P. koraiensis in Liangshui National Nature Reserve didn’t fluctuate very much during 320 years. The differentiation of genetic diversity is not obvious in age class level, and genetic diversity of P. koraiensis primarily existed within age class.