Abstract: We aimed to understand the influence of nitrogen levels on photosynthetic characteristics and chlorophyll fluorescence characteristics of rice leaf in different periods under salt stress. With two conventional japonica rice varieties from the north used as materials, the effect of five nitrogen levels were studied. Salt stress was applied at tillering, booting and heading. We studied the change in photosynthesis and chlorophyll fluorescence parameters of rice leaf. The net photosynthetic rate (P_n), stomatal conductance (G_s), transpiration rate (T_r) and apparent mesophyll conductance (AMC) were significantly reduced under salt stress as compared with controls. The percentage decrease of P_n, G_s, T_r and AMC during tillering, booting and heading was minimum of 2N, 1N and 1/2N levels. The stomatal limitation (L_s) of rice leaf was significantly increased under salt stress. The percentage increase in L_s during tillering, booting and heading was maximum of 2N, 1N and 1/2N levels. The PSII actual photosynthetic efficiency (ΦPSII), apparent photosynthetic quantum transmission efficiency (ETR) and photochemical quenching (qP) were significantly reduced under salt stress as compared with controls. The percentage decrease in ΦPSII, ETR and qP during tillering, booting and heading was minimum of 2N, 1N and 1/2N levels. The non-photochemical quenching (NPQ) was increased under salt stress. The percentage increase in NPQ during tillering, booting and heading was minimum of 2N, 1N and 1/2N levels as compared with controls. A moderate amount of reducing nitrogen levels was helpful to slow the decline of leaf photosynthesis and to improve the ability to resist salt injury after booting stage of rice under salt stress.