Abstract: Using the seedlings of Elaeagnus angustifolia; Lycium barbarum; Morus mongolica and Caragana korshinskii planted in mild saline-alkali land in the western part of Jilin Province as test materials, the differences and correlations of photosynthetic and chlorophyll fluorescence parameters of the four plants were studied, in order to reveal the photosynthetic performance of the four plants and provide a reference for the application of saline-alkali land greening plants. The results showed that there were significant differences in photosynthesis and chlorophyll fluorescence of the four plants. The net photosynthetic rate（P_n） was in the order of Lycium barbarum,Morus mongolica, Elaeagnus angustifolia and Caragana korshinskii. There was a significant positive correlation between net photosynthetic rate（P_n） and stomatal conductance（G_s）, so P_n was greatly affected by G_s, and P_n was closely related to fluorescence parameters such as maximum quantum yield of primary PSⅡ photochemistry under light adaptation; actual quantum yield of primary PSⅡ photochemistry(Ф_PSⅡ); photochemical quenching（q_P）; electron transfer efficiency(E_TR) and so on. The relative variable fluorescence V_j and V_i of J phase and I phase of Lycium barbarum were the lowest, the electron transfer efficiency of plastoquinone was high, the plastid plastoquinone（S_m） on the receptor side of PSⅡ was the highest, and the photosystem activity was the highest. The electron transfer efficiency of Caragana korshinskii was low, and the photoreaction activity was limited by the energy absorption of antenna pigment（ABS） and the energy capture of reaction center（TR）. At the same time, the performance index(P_{I ABS}) of Lycium barbarum was significantly higher than that of other tree species in the performance index(P_{I CSo}) based on initial fluorescence（F_o）and the performance index(P_{I CSm}) based on maximum fluorescence（F_m）, and Caragana korshinskii was the lowest. There were significant differences and extremely significant correlation among the three performance indexes of the four plants, and there was a significant correlation between P_n and P_{I ABS}, P_{I CSo}, P_{I CSm}. Therefore, P_{I ABS}, P_{I CSo}, P_{I CSm} was suitable to be used as an evaluation index of chlorophyll fluorescence characteristics of four kinds of plants. According to research, among the four plants, Lycium barbarum had the highest performance index P_I and P_n, and therefore had the strongest photosynthetic performance, followed by Morus mongolica and Elaeagnus angustifolia, and Caragana korshinskii was the lowest. Therefore, Lycium barbarum had strong photosynthetic physiological activity and was suitable for planting and introduction in the saline-alkali environment of this experiment.