Abstract: Taking Erigeron breviscapus as the experimental material, the diurnal variation law of Erigeron breviscapus photosynthesis was analyzed by LI-6800 portable photosynthetic analyzer, and the effects of temperature increase（22,26,30 ℃） on the photosynthetic physiological characteristics of Erigeron breviscapus were simulated, in order to provide reference for the cultivation of Erigeron breviscapus.The results showed that Erigeron breviscapus showed three peaks during the whole day, and there was a short photosynthetic lunch break.At 22-26 ℃,the light saturation point（LSP）,light compensation point（LCP）,maximum carboxylation rate（Vc_·max）,maximum electron transfer rate（Jmax） and Jmax/Vc_·max of Erigeron breviscapus gradually increased, while water use efficiency（WUE） gradually decreased.At the temperature of 22-30 ℃,the maximum photosynthetic capacity（Amax）,utilization rate(V_TPU) and transpiration rate（Tr） of Pn, LSP,Vc_·max, Jmax, Jmax/Vc_·max, LCP,CO₂ compensation point and triose phosphate gradually increased, while the maximum photochemical efficiency Fv/Fm of WUE and PSⅡ,the activity Fv/Fo of photosystem Ⅱ and the dark respiration rate（R_d） decreased.When the temperature was 26-30 ℃,Pn, Vc_·max, Jmax, V_TPU,Jmax/Vc_·max and LSP had no significant changes, LCP and Γ increased, while WUE,Fv/Fm, Fv/Fo and Rd decrease.Apparent quantum effect（AQE）,intercellular CO₂ concentration（Ci）,stomatal conductance（Gs） and the ratio of intercellular CO₂ concentration to atmospheric CO₂ concentration（Ci/Ca） had no significant changes at all stages.In conclusion, increasing the temperature could enhance the photosynthesis and photosynthetic utilization interval of Erigeron breviscapus,and promote plants to use stronger light energy.When the temperature was too high, Erigeron breviscapus would find photoinhibition, which might cause irreversible damage to plants.