This study was conducted to investigate the effect of meteorological factors on the diameter growth and Key-year in Pinus koraiensis and Pinus densiflora trees grown in Chuncheon and Hongcheon. The results obtained were summarized as follows 1. The diameter growth of Pizaus koraiensis was better than that of Pinus densiflora grown in the same meteorological condition and site environment. 2. The influence of meteorological factors on the diameter growth of Pinus koraiensis was the highest in the descending order fog, hours of sunshine, precipitation, relative humidity, warm index, and evaporation, 3. The influence of meteorological factors on the diameter growth of Pinus densiflora was the highest in the descending order fog, hours of sunshine, relative humidity, precipitation, and warm index, But evaporation was not significant, 4. The Key-years for Pinus koraiensis and Pinus densiflora trees appeared in 1964 and 1913 when the diameter growth was influenced by the specific climate change.