Spatiotemporal variations in the characteristics of fluorescent dissolved organic matter (FDOM) components from 63 lakes across the Tibet Plateau, China, are examined using excitation-emission matrix spectra (EEM) and fluorescence regional integration (FRI) from 2014 to 2017. Freshwater ( N = 135) and brackish water ( N = 109) samples from 63 lakes were grouped according to salinity or electrical conductivity. In order to compare results between the lakes, cumulative volumes beneath the EEM values (φ i , i = I, II, III, IV, V) were normalized to a DOC concentration of 1 mg/L. EEM-FRI identified tyrosine-like (φ I ), tryptophan-like (φ II ), fulvic-like (φ III ), microbial protein-like (φ IV ), and humic-like (φ V ) fluorescence regions, as well as their proportions (P i ). Chromophoric dissolved organic matter (CDOM) absorption parameters, fluorescence indices, average fluorescence intensities of the five fluorescent components and total fluorescence intensities (φ T ) differed under spatial variation among brackish and freshwater lakes (ANOVA, p < 0.05). Principal component analysis (PCA) was used to assess and group five normalized FDOM components for all of the water samples. These results show that microbial protein-like (φ IV ), fulvic-like (φ III ) and humic-like (φ V ) have positive correlations (R 2 > 0.79, t -test, p < 0.01), indicating that these FDOM components may originate from similar sources. A correlation also exists between normalized φ i ( i = I, II, III, IV, V) and DOC concentrations with a salinity > 19 ‰ (averaged EC, 23 764 μs cm −1 ) ( t -test, p < 0.01), of which R 2 f regression analysis showed a decreasing tendency with EC. Similar correlations between a (254) and DOC concentrations ( t -test, p < 0.01) are also evident for sunshine hours > 2900 h. Redundancy analysis (RDA) indicates that a (254) and a (350) have a correlation with CDOM in brackish lakes. a (254), HIX and a (350) were also correlated with water quality. Strong evapoconcentration, intense ultraviolet irradiance and landscape features of the Tibet Plateau may be responsible for the FDOM characteristics identified in this study.