Abstract: In order to study the effect of hydrogen addition on ethanol combustion, the kinetic analysis of ethanol blended hydrogen premixed laminar combustion at learn combustion condition was conducted by using CHEMKIN PRO code. The chemical effects and thermal/dilution effects of major and intermediate species in hydrogen blended ethanol flame were distinguished and discussed. Results show that the chemical effects of hydrogen addition promot the consumption of ethanol and production of intermediate species, shift the profiles of that to the upstream sides, also increase the reaction rates. However, the thermal/dilution effects inhibit the production of that and reduce the reaction rates. The combined effects of hydrogen additive make the chemical reaction begin in advance, inhibit the production of formaldehyde pollution.