This study takes the DOM of the Moguhu Lake water as an example, based on accumulative emission spectra (AFEs), combined with multivariate statistics and second derivative, to characterize the various fluorescent components and content of DOM. Principal Component Analysis (PCA) was used to analyze the factor loading of AFEs and to determine the difference between the types of fluorescent peaks and their contents. The second derivative AFEs are obtained by AFEs through second derivative conversion. Analysis of the content and variation of each component in DOM by absolute area integration of the fluorescence peaks of the second derivative AFEs of all sampling points. Cluster analysis was used to analyze the difference or similarity of DOM components at different points. Studies have shown that five types of fluorescent peaks are obtained by AFEs, namely protein-like peaks, fulvic acid-like peaks, marine or terrestrial humic acid peaks, and humic acid peaks. Based on the analysis of the AFEs and sum of fluorescence intensity, it can be seen that the DOM in the water of the Moguhu Lake is mainly unstable, easily degraded, and the protein with less molecular weight and fulvic acid. The degree of humification of its DOM is reduced from the lakeside area to the deep lake area. According to the AFEs score map, five types of fluorescent peaks are obtained, and the protein-like and fulvic acid-like peaks in the fluorescent peak are the main ones. Based on the point-score matrix, it can be explained that there is a difference in the fluorescence components between the points. The second derivative AFEs are divided into five fluorescent bands. The DOM is mainly composed of organic matter with small molecular mass, and the degree of humification and aromaticity are small, and the spatial difference is not significant. By clustering the fluorescence peak area and sampling points, the fluorescence peaks are divided into three categories, of which fulvic acid content is relatively large, and there is a difference between the shore sampling point and the sampling point located in the lake center area. In summary, AFEs are relatively simple and rapid, and can be used to characterize DOM instead of 3DEEM. The DOM in the water of the Moguhu Lake is mainly composed of protein-like and fulvic acid-like substances with relatively low molecular weight, instability and easy degradation. In general, the degree of humification and relative molecular mass have a tendency to decrease from the lakeside area to the deep lake area, but the spatial difference is small.