Laminar burning velocities of premixed ethanol-water-air flames over a range of equivalence ratios from 0.7 to 1.6 at 0.1 MPa and 383 K were determined experimentally at different water contents in a combustion chamber with central ignition. An ethanol oxidation mechanism was selected to simulate one-dimensional planar flames of ethanol-water-air mixtures under the same conditions to observe the effect of the water addition on the planar flame structure, the sensitivity of laminar burning velocity, and the net reaction rates of the elementary reactions. The physical effect of water was separated from its chemical effect by designing a type of fictitious water in the simulation. Results show that unstretched flame speeds and laminar burning velocities of the flames decrease with increasing the water content. When the water content was elevated, the peaks of the mole fractions of the main radical species gradually decrease and the net reaction rates of the elementary reactions with positive sensitivity coefficients decrease more than those of the elementary reactions with negative sensitivity coefficients. Both physical and chemical effects of water suppress laminar burning velocities of hydrous ethanol air mixtures, and the former dominates. The chemical effect of water promotes production of OH and has a much more remarkable influence on the reaction rates of the elementary reactions with negative sensitivity coefficients than on those of the elementary reactions with positive coefficients. The physical effect of water has an inhibiting effect on both the production of the radicals and the reaction rates of the elementary reactions.