Abstract: A method has been developed for the determination of lignin distribution in wheat straw cell walls by scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDXA) technique. This paper deals with the effects of bromination, section thickness and specimen grid holder on quantitative assay of lignin distribution. Results indicate that the combination of bromine for lignin is not only specific but stable, and the effects of backscattering. absorption and fluoresence on the quantitative analysis may all be ignored and the spatial resolution can be remedied by using thin speeimens. Therefore, the SEM-EDXA technique provides quantitative information of lignin distribution with relatively high accuracy.