The lignin of apricot shell was separated from apricot shell by sulfuric acid removal method to study the structure, pyrolysis characteristics and product formation of apricot shell lignin, and its structure and composition were confirmed by Fourier transform infrared spectroscopy(FT-IR) and nuclear magnetic resonance(NMR). The formation characteristics of pyrolysis products was studied by thermogravimetric and thermogravimetric-infrared spectroscopy. The results showed that the yield of apricot shell lignin was 30.42% by sulfate removal method. The FT-IR showed that the apricot shell lignin could be qualitatively determined guaiacyl unit and syringyl unit. The 2D heteronuclear single quantum correlation nuclear magnetic resonance (2D HSQC NMR) of apricot shell lignin indicated which contained syringyl(S), guaiacyl(G) and p-hydroxyphenyl proane(H). Apricot shell lignin pyrolysised in a wide temperature range between 150 and 650 ℃, and the pyrolysis process was mainly divided into three stages analyzied by thermogravimetric and thermogravimetric-infrared spectroscopy. The maximum thermal decomposition weightlessness temperature was 360 ℃, and H2O, CO, CO2, CH4, alcohols, aldehydes, phenols and acids were generated. The precipitation temperature range of CO occured in a wide temperature range between 200-700 ℃, that mainly created by the dissociation of the ether bond on the side chain of phenylpropane at the low temperature, and created by the dissociation of the ether bond between benzene rings and the volatile decomposed secondary. The precipitation temperature range of CO2 was narrow between 250-650 ℃, which mainly created by the fracture and rearrangement of the carbonyl and carboxyl on the side chain of phenylpropane. The precipitation of CH4 had two peaks, the one 400 ℃ was the dissociation of the side chain of phenylpropane and the demethylation of the methoxy on the benzene, and the other one 600 ℃ was rupturing deeply of the aromatic ring.