The yttrium-modified zirconia catalysts were prepared by co-precipitation method. N2 adsorption/desorption method, temperature programmed desorption and X-ray diffraction were used to characterize the Y/ZrO2 catalyst. All the catalysts were tested in the conversion of ethanol to propylene. The propylene yields showed a volcano-shaped dependence on the Y amount. The maximum yield of propylene reached 44.0%. The results implied that Y/ZrO2 catalyst with tetragonal structure or bigger specific BET surface area showed better performance. Reaction pathways were suggested to be ethanol to ethylene on the acidic sites, and ethanol→acetaldehyde→acetone→propylene on the basic sites.