In recent years, as the urban climate and environment have changed, research has increasingly focused on how plant leaf functional traits respond to climate conditions. This study compared two typical cities in Jiangsu Province—Suzhou, with a subtropical monsoon climate, and Suqian, with a temperate monsoon climate. We analyzed 11 leaf functional traits of eight landscape tree species. Using coeffi cient of variation analysis, t-tests, and principal component analysis, we found:(1) Leaf functional traits varied with the climate. In Suqian, traits like LA, LDMC, SLA, Pn, Gs, and SS showed higher variation coeffi cients. In Suzhou, traits such as SPAD, Tr, Cmass, Nmass, and SD had greater variation coeffi cients. On average, Suqian trees had higher SPAD, Pn, Tr, Cmass, Nmass, and SS, while Suzhou trees had higher LDMC and SD. (2) There were signifi cant synergistic and trade-off relationships between leaf functional traits. Plants adjusted their stomatal structure, photosynthetic capacity, and water-use strategies to adapt to diff erent climates. (3) Principal component analysis revealed diff erent adaptation strategies. Suqian trees adopted a “resource - acquisition - priority” strategy, enhancing photosynthesis and carbon/nitrogen accumulation to cope with alternating cold/dry and hot/humid conditions. Suzhou trees developed a “conservative - stress - resistance - priority” strategy, with high LDMC and SD to withstand the hot, humid climate. This study shows that plants adapt to climates through trait combinations, providing key theoretical support for selecting urban tree species and for climate-adaptive greening, especially in ecological restoration amid extreme climates.