Abstract: This study was conducted to investigate effects of different rate of super absorbent polymer (SAP) on leaf structural and functional traits of 4 greening plants (i.e. Malus‘Purple’, Sapium sebiferum, Photinia × fraseri, Catalpa bignonioides). The results showed that the SAP had significant effect on the leaf structural traits (such as leaf area, chlorophyll content, specific leaf area and Gs) and functional traits (such as Pn, Tr and WUE) of Malus‘Purple’, Sapium sebiferum, Photinia × fraser and Catalpa bignonioides. 0.1% SAP content added to the soil could remarkably improve leaf structural and functional traits of the 4 greening plants. Applied with 0.2% SAP content, Photinia × fraser and Catalpa bignonioides had higher leaf area, chlorophyll content, specific leaf area, Gs, Pn and Tr than that of the CK or applied with 0.1% SAP, while applied with 0.3% SAP content, the above-mentioned index were close to that of 0.2% SAP content. Meanwhile, applied with 0.2%- 0.3% SAP content, above- mentioned index of Malus‘Purple’and Sapium sebiferum were significantly lower than that of the 0.1% SAP content and close to that of the CK. These indicated that Photinia × fraseri and Catalpa bignonioides more adapted to the moist soil than Malus‘Purple’and Sapium sebiferum. But Malus‘Purple’and Sapium sebiferum more adapted to dry soil than Photinia × fraseri and Catalpa bignonioides because of their WUE magnified significantly in CK than that of SAP applied. The significant change of specific leaf area between CK and SAP applied with different rates in the 4 greening plants indicated the capability of obtaining resource and promoting growth in moderate soil moisture and adaptation to water stress.