Dissolved organic matter (DOM) is pivotal in aquatic ecosystems and biogeochemical cycles. Understanding the composition characteristics, sources, and influencing factors of DOM in typical lakes and reservoirs across northern China is crucial for effective organic matter pollution control and safe water transfer. This study collected 130 surface water samples from eight representative water bodies: Xiaoxingkai Lake, Songhua Lake, Dahuofang Reservoir, Guanting Reservoir, Yuqiao Reservoir, Baiyangdian Lake, Hengshui Lake, and Nansi Lake. The key findings are as follows: (1) Through parallel factor analysis (PARAFAC), three distinct fluorescent components were identified in the DOM of these lakes and reservoirs: humic-like substances (C1), tryptophan-like substances (C2), and tyrosine-like substances (C3). DOM in northeastern lakes and reservoirs exhibited strong humification characteristics with relatively low autochthonous contributions, while those in North China demonstrated pronounced autochthonous features. Notably, Baiyangdian displayed unique DOM characteristics with higher DOM content and protein-like components than other studied water bodies. (2) Humic-like substances from anthropogenic sources significantly positively correlated with CODMn and HIX. Protein-like components (C2, C3) showed significant positive correlations with DOC, FI, and BIX but negative correlations with HIX. DOM components correlated more strongly with nitrogen than phosphorus nutrients. (3) A larger watershed area extends the retention time of dissolved organic matter (DOM) in lakes, promoting the accumulation of endogenous DOM components, while deeper water bodies facilitate the preservation of DOM. Elevated temperatures enhance the in-lake transformation of DOM, intensifying its endogenous characteristics and reducing its exogenous features. In regions with higher precipitation, rainfall-runoff transports terrestrial humic substances into water bodies, increasing the exogenous DOM signature. Aquatic vegetation and microorganisms predominantly influence DOM dynamics through endogenous processes, collectively regulating nutrient cycling and ecological functions in aquatic systems. Human activities introduce substantial amounts of organic matter into water bodies, altering the characteristics of DOM. Agricultural practices enhance the endogenous DOM signature by stimulating microbial metabolism; areas with high vegetation coverage contribute more terrestrial humic-like components to water bodies; and urban areas introduce substantial amounts of organic matter and pollutants, modifying the composition and characteristics of DOM.