A field experiment was conducted to investigate the effects of enhanced UV-B radiation on diurnal variations of net photosynthetic rate (P_n), stomata conductance (G_s), intercellular CO₂ concentration(C_i), transpiration rate (T_r), and water use efficiency (E_wu) of peanut leaves at fruiting stage of different peanuts cultivars, so as to provide a basis for screening out high-yield, drought-resistant and UV-B-radiation-resistant peanut varieties.The experiment was designed with two levels of UV-B radiation, natural light (CK) and enhanced UV-B radiation by 20% (E).The results showed that enhanced UV-B radiation inhibit photosynthesis and transpiration of peanuts significantly.The daily average P_n of KaiNong No.49, 64, and 69 declined by 19.4%, 27.8%, and 24.7%, respectively;the daily average G_s decreased by 26.7%, 42.9%, and 28.6%, respectively.Besides, the daily average C_i of KaiNong No.49, 64, and 69 declined by 27.2%, 20.4%, and 23.1%, respectively, and the T_r decreased by 17.8%, 23.3%, and 25.1% respectively.Furthermore, the E_wu reduced by 16.6%, 23.2%, and 23.9% for KaiNong No 49, 64, and 69, respectively.These results indicate that enhanced ultraviolet-B radiation have a restraint effect on these three cultivars, but sensibility differences exist among these peanuts cultivars.Therein, KaiNong No.49 is the least sensitive peanuts cultivar.Therefore, compared with the other two cultivars, KaiNong No.49 shows great advantages in regard to UV-B radio-resistance.