Industrialization and rapid urbanization have led to the exposure of urban tree species during their growing seasons under high concentrations of surface ozone (O₃) and nitrogen (N) deposition conditions. To understand the combined effects of elevated O₃ and N deposition on urban trees, two common urban tree species in Beijing, Koelreuteria paniculata and Pinus bungeana, were selected as experimental materials from May to September 2022. We utilized open-top chambers (OTCs) and the ¹⁵N isotope tracing method to investigate the variations in the photosynthetic physiology and leaf N distribution of the two tree species under three different O₃ exposure concentrations: NF (ambient O₃ concentration), NF40 (NF + 40 nmol/mol O₃), and NF60 (NF + 60 nmol/mol O₃). The results showed that: (1) At the end of the growing season, both K. paniculata and P. bungeana exhibited significant inhibition of leaf light-saturated photosynthetic rate (A_sat), stomatal conductance (g_s), chlorophyll content (Chl a+b), carotenoid content (Car), and biomass by elevated O₃ concentrations. However, there was an increase in leaf N content and δ¹⁵N abundance. (2) K. paniculata and P. bungeana adopted different strategies for N absorption at the end of the growing season. K. paniculata absorbed more N in new leaves compared to old leaves, and nitrogen might be transferred from old leaves to new leaves before old leaves fall down to the ground. In contrast, P. bungeana stored relatively more N in old leaves to maintain evergreen foliage rather than transfer it to the new leaves. (3) During one week before the growing season finished, the elevated O₃ accelerated leaves senescence of K. paniculata whether N addition or not, and with the O₃ concentration increased the senescence rate increased. However, N addition could alleviate the negative effect of elevated O₃. This pattern was shown much more clearly when the growing season nearly finished. When simulating the response of urban tree species to the increased O₃ concentrations and N deposition, it is essential to consider differences in functional types, such as deciduous and evergreen species, as well as the growth period of plants, especially during the late growing season.