The photodecompositions of 2,4,6-trichlorophenol (2,4,6-TCP) in pure water, dissolved organic matter (DOM) solution, and actual surface water were studied comparatively. The results indicate that there are three pathways in the photodecomposition of 2,4,6-TCP, including direct photolysis, sensitized photolysis, and self-sensitized photolysis. Direct photolysis and self-sensitized are found to be involved in the photolysis of 2,4,6-trichlorophenol in pure water, with singlet oxygen as main active species. Besides direct photolysis, sensitized photolysis of 2,4,6-trichlorophenol is also found in presence of DOM with singlet oxygen and hydroxyl radical as main active species. The degradation rates of 2,4,6-trichlorophenol in pure, DOM-contained and actual surface water all increase with the oxygen content in solution. The visible light has no contribution for the direct photolysis of 2,4,6-TCP, and UVA contribution is 72.60%. While in presence of dissolved organic matter, about 12.39% contribution of visible light is found, and the contribution of UVA is 52.73% in DOM solution. The photolysis of 2,4,6-trichlorophenol in actual surface water is similar to that in DOM solution, in which DO and DOM are the dominant factors in the indirect photolysis of 2,4,6-TCP.