Mongolian oak is one of the most important broad-leaved tree species in forests,Northeast China. Based on the methodology of dendrochronology,the variations of tree ring radial growth of Mongolian oak in Qianshan Mountains,south of Northeast China,were analyzed. Combined with the temperature and precipitation data from meteorological stations since 1951,the relationships between standardized tree ring width chronology and main climatic factors were analyzed. In this region, the precipitation between April and July of the current year had an significant relationship with the tree ring width of Mongolian oak,and was the main factor limiting the radial growth. The extreme maximum temperature of May was also a key factor influencing the tree ring width,which had a significant on the tree ring width of Mongolian oak. The precipitation in April had a significant and stable relationship with the growth of Mongolian oak since the 1950s. The'divergence problem'was found in the study area,which the sensitivity of tree growth to summer temperature reduced since the 1980s. The tree growth response to temperature showed a seasonal change from summer to spring.