In order to reveal the influence of the structure of the modified lignin GCL1-JB on its adsorption characteristics and dispersion stability, a series of GCL1-JB of different conformations were prepared by adding dioxane into the aqueous solution of GCL1-JB. Then, the dispersion stability of cement/GCL1-JB suspension and the adsorption characteristics of GCL1-JB of different conformations were determined by using a TurbiscanLab analyzer and by means of the sequential adsorption process. The results show that with the increase of the stretch conformation of GCL1-JB, the amount of GCL1-JB adsorbed on a solid surface decreases while the dispersion stability of GCL1-JB for cement particles increases. In addition, the GCL1-JB of more stretch conformation can adsorb flat  and forms a compact and smooth film, thus effectively preventing cement particles from agglomerating. This is why the dispersion stability of GCL1-JB is superior to that of sodium lignosulfonate.