Abstract: To explore the change rule of phenophase ofPinus koraiensis seedlings and provide a scientific basis for correct sowing, seed collecting, planting and cultivation in forestry production, based on the phenophase data of Pinus koraiensis seedlings and the climate at the same time in Xiao Hinggan Mountains from 1991 to 2014, the responses of Pinus koraiensis seedlings’phenophase to meteorological conditions were discussed by correlative analysis and optimal subset regression. The results showed that: (1) the beginning period of bud opening and the flourishing period of new shoot lignification of Pinus koraiensis seedlings were delayed, the beginning period of leaf spreading and the flourishing period of new shoots formation were advanced, the whole growing season was prolonged; (2) except the beginning period of bud opening and the flourishing-formation period of apical bud, the correlation was found to be significantly positive between the other phenophases and sunshine hours during the corresponding period, the correlation was found to be significantly negative between the flourishing-formation period of apical bud and temperature. The two main factors influencing the length of the whole growth period were the accumulated temperature of ≥10℃ and the daily minimum temperature, followed by sunshine hours and the average temperature. The regression equations were established between the Pinus koraiensis seedlings’phenophase and the meteorological factors based on the optimal subset regression.