To study the influence of transgene on lignin content of poplar,experimental materials were taken fromdifferent poplars in different heights.Three discs were taken from different heights first,then selecting materialsfrom the discs in different rings.Remove the epidermis,phloem and pith.Small wooden staffs were taken fromdifferent rings,and grinded to wood flour.Chemical titration method,FTIR spectroscopy and T-test wereconducted on specimens of non-transgenic poplars and transgenic poplars.The results showed that The relativelignin content of transgenic plants is not significant different with non-transgenic plants.Chemical titration canaccurately measure the lignin content of wood,and compare with each other,but the process is complex.AlthoughFTIR spectroscopy can not accurately determinate lignin content of wood,we can contrast lignin content ofdifferent experimental groups through the characteristic peaks.The operate process is relatively simpler thanchemical titration.Generally,little difference was shown between the lignin content of transgenic plants andnon-transgenic plants.Different plant has obvious effects on the lignin content.Different rings have obviouseffects on the relative contents of lignin,results indicate that the closer to pith,the higher of lignin content.In thewood with three rings,the lignin content has little difference between the outer two rings,while the lignin contentof the inner ring is obviously higher than that of the outer two rings.