Abstract: Based on the research of Pinus koraiensis seed bank, the paper has studied on the pattern and its dynamic of Pinus koraiensis seedling and sapling distribution; Pinus koraiensis population age structure in juvenile stage and the relationship between juvenile Pinus koraiensis and their environment. Near one thousand quadrats of 4m² and 7 plots of 20×20m² were investigated, 388 seedlings and saplings were measured concerning biomass and age. As a result the process of Pinus koraiensis natural regeneration and the mechanism of "regeneration complex", it says that the Pinus koraiensis natural regeneration can be carried out under the broad leaved forest, have been discussed. The research is important to reveal the self maintain process of Pinus koraiensis, an ageold population.