Rosa chinensis Jacq and Euonymus japonicus L were grown in pots with different levels of water stress to evaluate the effects of soil water stress on photosynthetic physiological characteristics. Results are showed as follows:(1) According to the daily average of photosynthetic parameters

the Pn and Tr of the two plants gradually decreased with the increase in water stress. The WUE of Euonymus japonicus gradually decreased

but Rosa chinensis Jacq

increased first and then decreased. The Gs of Rosa chinensis Jacq gradually decreased

while Euonymus japonicus L had higher value in moderate water stress (W2) than in mild water stress (W1). The Ci of Rosa chinensis Jacq first decreased and then increased

while Euonymus japonicus L gradually increased. (2) The chlorophyll fluorescent parameter

Fo

increased

while Fm

Fv

Fv/Fm

and Fv/Fo decreased due to water stress

but Euonymus japonicus L had greater change than Rosa chinensis Jacq. (3) The diurnal variation curves of photosynthetic parameters of the two plants were significantly different. The diurnal variation curves of the Pn and Tr of Rosa chinensis Jacq were the double-peak type and Euonymus japonicus L

the single-peak type in normal water supply (CK) and mild water stress (W1). (4) The changes of fluorescent parameters and photosynthetic parameters of the two plants under water stress revealed that Euonymus japonicus L was more sensitive to soil water stress than Rosa chinensis Jacq.