In this work,we performed period Density Functional Theory calculations to explore reactive pathways of ethanol to catalytically form 1,3-butadiene on ZrO2 surface with Dmol3 in Materials Studio.The overall energy barrier and reaction energy were explored for aldol condensation mechanism and Prins condensation mechanism.In particular,we identified aldol condensation mechanism is dominant compared to Prins condensation mechanism on ZrO2 surface.We explained the better catalytic performance of two-step process from ethanol to form 1,3-butadiene than one-step due to more active reactivity of acetaldehyde added in reactants.It is verified that ethylene is by-product instead of intermediate product,and crotonaldehyde can promote ethanol to form acetaldehyde via MPV reaction,as well as decreasing ethylene formation from ethanol.Finally,we revealed that proton transfer step from carbon chain to catalyst surface is the rate-limiting step from ethanol catalytically to form acetaldehyde on ZrO2 catalysis.Therefore,we proposed dope the second catalytic dehydrogenating promoter into ZrO2 based catalysis would improve the performance of catalysis.