The hydrology and hydrochemistry of wetlands show significant differences in time and space scales, which will lead to changes in photochemical reactions. Photochemically produced reactive intermediates (PPRIs) are the products of indirect photoreaction in water bodies and have strong oxidation properties. They have an important impact on the regression of organic matter and pollutants in the water environment, so it is imperative to explore the production process of PPRIs in wetlands. In this study, the production rate and steady-state concentration of three kinds of PPRIs (¹O₂, ·OH and ³CDOM^*) in water during spring, summer, autumn and winter of Lake Poyang wetland were monitored using trapping agent method. The chemical characteristics of dissolved organic matter (DOM) in water were analyzed by ultraviolet absorption spectrum, three-dimensional fluorescence spectrum and fourier transform ion cyclotron resonance mass spectrometry. The photochemical reaction properties of DOM in water at different seasons in the Lake Poyang wetland and the correlation between DOM and PPRIs had been revealed. The results showed that pH value and dissolved organic carbon (DOC) contents of Lake Poyang were higher in summer and autumn, while nitrate and nitrite concentrations were lower in summer and autumn. The abundance of aromatic compounds was higher in DOM during summer and autumn, and the lignin abundance was significantly higher than that during winter and spring. The production capacity of colored soluble organic matter in Lake Poyang in different seasons was in the order of autumn >summer >winter >spring. The production rates and steady-state concentrations of ¹O₂ and ·OH in summer and autumn were significantly higher than those in spring and winter. pH, DOC, E2/E3, lipids, proteins, and ligins showed a good positive correlation with the production rate of PPRIs. In addition, from the three-dimensional fluorescence index results, fluorescence index (FI) and freshness index (β/α) showed a negative correlation with PPRIs, which proved that the lower FI value and the higher land-based DOM caused the higher the PPRIs generation rate. In summary, the photochemical production of PPRIs was closely related to the DOM of plant sources. Compared with spring and winter, the water organic matter of Lake Poyang was higher in summer and autumn. The aromatic compounds and humus in DOM components were also more abundant in spring and winter, mainly from terrestrial plants and soil organic matter. These DOM were mainly from the lake itself and generated by microorganisms, which belonged to the internal source. Organic components released during the degradation of flooded plant residues had an easily overlooked effect on the origin and composition of DOM in summer and autumn, and those with strong photochemical activity, such as lignin, were the main reason for the higher yield of PPRIs.