Abstract: In order to improve the catalytic cracking effect of semi-coke from lignite pyrolysis on tar,the semi-coke prepared by coal pyrolysis was used to catalyze the pyrolysis of coal tar.Two-stage fixed bed reactor was used to study the effects of coking temperature,char consumption and oxygen activation on the catalytic cracking of tar.Coal samples were placed in the upper section of the reactor for pyrolysis,and semi-coke catalyst was placed in the lower section to catalyze the pyrolysis of tar produced in the upper section.The results show that the yield of tar decreases obviously with the increase of coking temperature of lignite.The yield of tar is only 6.3% when the activated semi-coke prepared from lignite at 900 ℃ is 1 g.Increasing the coking temperature is beneficial to the catalytic cracking of macromolecular aromatics in tar into less-loop substances and small-molecule components.Increasing the char consumption has no obvious effect on tar removal,the tar yield decreases slowly.Compared with the unactivated char,the char activated by O_2 has better removal effect on tar.Specific surface area and pore analysis of semi-coke( BET) show that the activated char has larger specific surface area and more pore space.Energy spectrum analysis( EDS) shows that the total amount of metal elements on the surface of activated char is higher than that of unactivated char.