Abstract: Catalytic behavior and effects of K+ and Ca2+ in the process of cellulose pyrolysis were studied in an infrared radiation pyrolysis system. In the case of medium pyrolysis temperature, catalysis of potassium salt and calcium salt mainly occurred in solid phase, only few ions were released out of solid particles and entered into the liquid or gaseous products, which is beneficial for clean liquid fuel production from biomass. Both ions present the same catalysis behavior on biomass pyrolysis, as restrained formation of aqueous oil and enhanced production of char and gas. Besides, the quality of liquid product was improved by de-oxygen reaction catalyzed by K+ and Ca2+. In addition, K+ enhanced the cracking and disproportionating process of molecules to improve the production of hydroxyacetaldehyde, acetaldehyde and small-molecule components including groups of alcohols, ketones or aldehydes, while Ca2+ mainly influenced the rearrangement and isomerization of the monomeric sugar fragments to yield more furan and heterocyclic compounds. The selective catalysis behavior makes it possible to optimize biomass pyrolysis by selecting appropriate operation condition and metallic salts.