Abstract: Taking cucumber ‘Jinyou No.101’ as the test materials, based on the pot experiment, the dynamic changes of relative chlorophyll content（SPAD）,net photosynthetic rate（Pn）,stomatal conductance（Gs）,transpiration rate（Tr）,maximum fluorescence value（Fm） and maximum photochemical efficiency（Fv/Fm）of cucumber ‘Jinyou No.101’ leaves were respectively analyzed in treatment CK(0 kg·hm^-2),N1(90 kg·hm^-2),N2(180 kg·hm^-2),N3(270 kg·hm^-2),N4(360 kg·hm^-2) and N5(450 kg·hm^-2); and the responses of oxygen evolution complex（OEC） activity, energy transfer in photosystem Ⅱ（PSⅡ） thylakoids and terminal electron acceptor in photosystem Ⅰ（PSⅠ） of cucumber leaves to the N application were also discussed according to the fluorescence kinetic curve, in order to provide reference for the optimal management and improve nitrogen use efficiency of cucumber in greenhouse.The results showed that the N application could significantly increase the cucumber yield by 1.7-2.8 times, when the N application was 312 kg·hm^-2,the yield of cucumber was the highest.With the increasing of N applicatin, the SPAD value, Pn, Gs, Tr, Fm and Fv/Fm of cucumber leaves tended to rise first and then declined; especially the Pn, Gs, Tr and Fm of cucumber leaves in treatment N3 were significantly higher than those of other treatments.Based on the analysis of fluorescence kinetic curve, it was found the values of ΔW_O-Jin treatment N1 and N2 were positive, and the oxygen releasing complex（OEC） was inactivated; but ΔW_O-J and ΔW_O-Kin treatment N3 were negative, and the OEC was active and the energy was most smoothly transferred between thylakoids.Therefore, the optimum nitrogen application amount of cucumber ‘Jinyou No.101’ was 270-310 kg·hm^-2,considered the highest yield and the optimum photosynthenic efficiency.