The invention relates to a dispersing agent for water-based color paste and a preparation method of the dispersing agent. According to the dispersing agent containing the hydrophilic and hydrophobic chain segments and capable of being specifically combined with the
pigment particles, a
polymerization product with narrow molecular
weight distribution is obtained based on RAFT
polymerization, and the problem that organic
pigment is prone to agglomeration in a color paste
system is avoided through wrapping of the hydrophobic chain segments of polyether in the structure on the
pigment particles; a polyether
solvation chain segment is introduced into the structure of the dispersing agent, so that the storage stability of the dispersing agent in a water phase is ensured; the high approximation of the
acridone structure and common pigment structures such as
quinacridone and isoindolinone ensures the
coating effect of the dispersing agent on pigment particles, the dispersing agent has good dispersibility and compatibility in different aqueous systems, a specific dispersion effect is formed, the problems of high
viscosity, difficult dispersion and the like of organic pigments in the aqueous systems are effectively solved, and the dispersing agent has good application prospects. The dispersant can be used as a dispersant or an additive of systems such as water-based color paste and water-based ink. The method can be widely used in the fields of inks and paints.