To investigate the effect of colloid on uranium (VI) transport in saturated porous media in the presence of soluble organic matter, two kinds of quartz sands (fine sand and coarse sand) were selected, and the column experiment with homogeneous configuration was constructed to study the effect of kaolinite colloid on the U(VI) migration in two quartz sands with different particle size in the presence of humic acid under saturated water flow. The results showed that the breakthrough curves of tracer in two homogeneous columns were similar and symmetric. When the U(VI) solution only was introduced into the column, the mobility of U(VI) in the two columns was small (<25%), and a large amount of U(VI) were adsorbed on the quartz sand through surface complexation. When humic acid and kaolinite colloids were present in the U(VI) solution, the transport amounts of U(VI) in both two columns were increased, and the transport amount (58.36%) in the quartz sand with 600~850 μm was more than that (42.68%) in the quartz sand with 250~425 μm. This demonstrated that humic acid-kaolinite colloids and sand size had large influence on uranium migration in subsurface environment.