A anionic polyurethane dispersions were prepared from isophorone diisocyanate (IPDI), polyethylene glycol 200, 400, 600, 800 (PEG), dimethylpropyl acid (DMPA), 1-phenyl-1,2-glycol, neutralizer (TEA), methylketoxime and so on. The structure and properties of the dispersant were characterized by FTIR、GPC and TG. The liquid indigo dispersion was prepared by grinding method with the self-made dispersant. The influence of the chain length and amount of the dispersant on the performance of the dispersion was discussed. After grinding for 1h, when the amount of polyurethane dispersant synthesized with polyethylene glycol 400 as the soft segment was 60% of the amount of dye, the particle size of liquid indigo prepared was 277.1 nm, the centrifugal stability at 1000 r/min was 94%, and the centrifugal stability at 3000 r/min was 51%. After being placed at room temperature for 7 days, the particle size changed within 20 nm, and the K/S of the dyed fabric was about 10, which was twice that of powdered indigo, The color properties of the dyed fabric did not change. SEM showed that the particle size distribution of the dispersion was uniform. There was little difference in the stability of the dispersion system compared with the formaldehyde condensate (MF) of sodium methylnaphthalene sulfonate and lignin 85A.