Using open-top air chamber (OTC) to simulate the growth environment with elevated temperature and carbon dioxide (CO_2)concentration, and taking simulated field environment as control (CK), through field in-situ simulation experiments, highland barley variety Zang Qing2000 was observed under the environment of increasing temperature by 2℃(T2), 4℃ (T4)and 2℃ and increasing CO_2 concentration by 100muL·L~(-1)(T2+CO_2), and the changes of growth period, photosynthesis, agronomic traits and soil nutrients in the tillage layer of highland barley under climate change environment were analyzed. The results showed that the growth period of highland barley was shortened by 5-7 days under the warming treatment (T2, T4, T2+CO_2). Among them, T4 treatment had the shortest growth period of 92d, and T2 and T2+CO_2 treatment had 94d. Photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (GS) of highland barley leaves decreased significantly compared with CK during the warming treatment. Warming treatment significantly reduced the content of organic matter and available potassium and increased the content of available phosphorus in the soil tillage layer. Compared with CK, the yields of highland barley in T2, T4 and T2+CO_2 treatments decreased by 31.4 %, 46.9 % and 39.4%, respectively. Raising the temperature by 2℃ can improve the agronomic traits(plant height, dry matter quality and ear length) of highland barley, but increasing CO_2 concentration on the basis of raising the temperature has no significant effect on highland barley, and raising the temperature by 4℃ will seriously affect the normal growth and yield of highland barley.