The differences in mechanical properties between juvenile and mature wood of Korean Pine （Pinus Koraiensis） from plantation and natural forest were analyzed. A basic tendency exhibited by all of the properties was: the properties index of mature wood were much better than that of juvenile wood. The difference in MOE of plantation Korean Pine reached 0.01 level of significance while MOR and tangential crushing strength reached 0.05 level of significance. The difference in MOE of natural Korean Pine also reached 0.01 level of significance and MOR, radial crushing strength, hardness of cross section and tangential crushing strength reached 0.05 level of significance.