Abstract: In order to accurately reveal the pyrolysis process of chlorogenic acid (CGA),the pyrolysates of CGA were analyzed at ten temperature ranges,which were divided on the basis of thermogravimetric curve and pyrolytic characteristics of CGA,by an online gas chromatography/mass spectrometry (GC/MS).The results indicated that:1) The pyrolysis process of CGA could be divided into at least 6 temperature ranges,at which the weight-loss of CGA were 2.94%,0.61%,8.55%,20.29%,34.32% and 9.43%,respectively.2) The major components produced at the ten temperature ranges were as follows:Only water was observed at 30-120℃; no products were detected at 120-190℃; water,carbon dioxide and quinide-like compounds were formed at 190-260℃; carbon dioxide,phenol,catechol,hydroquinone,water and quinide-like compounds were released at 260-325℃; comparing with the products at 260-325℃,3-hydroxy benzoic acid,benzoic acid and 4-ethyl catechol were new at 325-400℃; 27 major pyrolysates were identified at 400-500℃, besides primary products,these were secondary products,such as 1,3-cyclopentadienes,furan,alkyl phenols,methyl catechols,benzoic acids,aromatic hydrocarbons and multi-benzene ring compounds; the concentrations of carbon dioxide,water and carbon monoxide were higher,which followed by phenol,catechol and 3-methyl phenol at 500-600℃; the main volatile components were water,carbon dioxide and carbon monoxide,and there were also a small quantity of benzene,toluene,phenol and 3-methyl phenol at 600-700℃; only water,carbon dioxide and carbon monoxide were observed at 700-800℃ and 800-900℃.The gradient pyrolysate analysis combining with thermogravimetric analysis could provide more information for investigating the pyrolysis process of CGA.