In order to solve the research limitations caused by overlapping fluorescence peaks of synchronous fluorescence spectroscopy, the overlapping peaks were analyzed by using synchronous fluorescence technology in combination with two-dimensional correlation and principal components and other methods to study the composition and structural characteristics of soil dissolved organic matter (SDOM). The typical and common reeds, poplar, corn, melon four planted soils in hetao irrigation area were selected as the research objects, and soil samples from the four sample points were collected, a total of 16 soil samples were collected under four layers of vegetation, namely 0~20, 20~40, 40~60 and 60~80 cm. Dissolved organic matter was extracted and Synchronous fluorescence spectroscopy (SFS) was detected. SFS showed that melon and corn SDOM fluorescence intensity was greater than the woodlands and reed, melon SDOM fluorescence intensity increased with the increase of soil depth, while for the other three plantings SDOM fluorescence intensity decreased with the increase of soil depth, indicating that for the melon soil,in the process of watering soil layer gave priority to eluviation, and other soil layers gave priority to filtration. Principal component analysis (PCA) was used to identify five fluorescence components, including tyrosine, tryptophan, microbial metabolites, fulvic acid and humic acid. Based on two-dimensional correlation spectrum analysis, tryptophan in reed soil was positively correlated with the change trend of microbial metabolites. The change order of spectral bands was 370 nm→337 nm→290 nm, indicating that the change order of components was fulvic acid→microbial metabolites→tryptophan. There was a positive correlation between fulvic acid and humic acid in maize soil, and the change order of the band was 318 nm→350 nm→420 nm→274 nm, indicating that the change order of components was microbial metabolites→fulvic acid→humic acid→tyrosine. There was a positive correlation between tyrosine, fulvic acid and humic acid in woodland soil, and the change order of band was 270 nm→392 nm→426 nm→305 nm→337 nm, indicating that the change order of components was tyrosine fulvic acid→humic acid→tryptophan→microbial metabolites. There was a positive correlation between humic acid and humic acid, but a negative correlation between humic acid and tyrosine in the soil of melons, and the change order of band was 410 nm→355 nm→334 nm→309 nm→275 nm, indicating that the change order of components was humic acid→fulvic acid→microbial metabolite→tryptophan→tyrosine. Therefore, it is very effective to analyze the fluorescence spectral characteristicsof SDOM and identification of fluorescence componentby using SFS combined with PCA and two-dimensional correlation spectroscopy, and to reveal the spatial variation law of fluorescence components.