Abstract: In this paper,the pyrolysis reaction of straw in the ionic liquid chloro-1-allyl-3-methyl imidazole(AMIMCl) was mainly studied.The effects of temperature,straw and ionic liquid mass ratio and reaction time on product yield were investigated,and optimal process conditions were got as following: straw and ionic liquid mass ratio was 0.4,the thermal decomposition temperature was 230 ℃,and reaction time was 30 min.The yield of bio-oil was 28%-30%.The product of pyrolysis obtained by experiment using GC-MS was analyzed,and the results showed that the composition of bio-oil was complex.There were alcohol,phenols,ethers,esters and aromatic substances in bio-oil.Ionic liquid can be recycled.