Micromixing efficiency of viscous media in Y-type micro-channel reactor was studied by using iodide-iodate test reaction as working system. Experiments were carried out in water-glycerin mixtures with 7 different viscosities. The experimental results showed that segregation index of the micro-channel reactor increases with the decrease of volumetric flow rate and the increase of solution viscosity. Based on the incorporation model, the micromixing time t(m) of the micro-channel reactor was estimated in the range of 10(-4)-10(-3) s at different viscosities, which indicated that the micro-channel reactor possesses a much better micromixing performance compared to the stirred tank (t(m) = 0.02-0.2 s).