Urban shading is caused by urban artificial constructive structures and has definite effects on the photosynthetic processes of plants. We used Li-6400 portable photosynthesis system to study the changes in ecological factors and photosynthetic characteristics of Euonymus japonicas planted in different levels of urban shading in Beijing. The results showed that: (1) The pattern of buildings or infrastructures' layout resulted in the differences of ecological factors under different levels of urban shading, mainly represented by temporal distribution and intensity of photosynthetically available radiation (PAR) and atmospheric temperatures. (2) Different levels of urban shading caused the changes in several main photosynthetic parameters of E. japonicas such as net photosynthesis (Pn),presenting an irregular single-peaked curve. When urban light environment changed from shading into direct sunlight, Pn showed an obvious increase and reached a peak value rapidly. The time point of the maximum value of Pn was delayed with the increasing level of shading. The Pn value of plants in the highest level of urban shading (S4) was the lowest in the four sites. (3) The leaves of E. japonicas showed a good ecological adaptability under a moderate urban environment of shading with a certain length of time (2.3 hours and 5.5 hours) when exposed to direct sunlight, and there was no significant variability among some indicators such as daily average of Pn, light compensation point (LCP), P_nmax, leaf area (LA) and leaf mass per area (LMA). The leaves of E. japonicas well adapted to the changes in urban shading environment with a shortened period ( to 2.3 h) of direct sunlight mainly by changing the contents and composition of photosynthetic pigments, namely, Chl a and Chl b, Chl a+b and Car/Chl. (4) Different levels of urban shading caused the changes in adaptive strategies of E. japonicas. When there was no direct sunlight appearing, a highest level of shading, E. japonicas presented obvious adaptive changes in its physiological photosynthetic processes, morphology, photosynthetic pigments and so on, and this type of the greatest shading caused by urban buildings or other infrastructures can obviously affect the growth of plants.