Abstract: In order to clarify the impact of temperature and precipitation pattern changes on the photosynthesis and chlorophyll fluorescence characteristics of Quercus mongolica seedlings, we analyzed light response curve and its characteristic parameters and chlorophyll fluorescence parameters and photosynthetic pigment content of Q. mongolica seedlings by artificial simulation method of temperature increase (2, 4, 6 ℃) and precipitation changes (+30%,-30%). The results showed that: Temperature treatment had no significant effects in addition to nonphotochemical quenching (qN) in July and apparent quantum efficiency (AYQ), showing a significant impact on the other parameters; precipitation treatment had a significant effect on actual photochemical efficiency (Yield) in September, photochemical quenching coefficient (qP), chlorophyll a, chlorophyll b and total chlorophyll content; interaction of temperature and precipitation had a significant effect on the maximum net photosynthetic rate (Pmax), Yield, qN and qp in July, maximum photochemical efficiency (Fv/Fm), Yield, qN and qp in September and chlorophyll a, chlorophyll b and total chlorophyll content. These results showed that the majority of characterization parameters of Q. mongolica seedlings showed some advantages in the temperature increase of 4 ℃, but when the temperature increased by 6 ℃, Pn, Pmax, AYQ and Fv/Fm, Yield and qp measured in July of all precipitation processing were lower than temperature control group. Within the range of +30% and -30% of precipitation processing, moderate warming is good for seedling growth of Q. mongolica, especially when the temperature increases by 4 ℃.