A pigment dispersing agent, a pigment dispersion solution, a color photoresist, and a process for manufacturing the same, and use in the color film substrate and display device. The pigment dispersing agent is an amino-β-cyclodextrin modified polymethacrylate, the amino-β-cyclodextrin modified polymethacrylate being used to disperse a powdered pigment having an aromatic group, wherein the degree of modification by amino-β-cyclodextrin is 5.36%-35.40%. Because β-cyclodextrin moiety is a group having affinity for pigments, it can bind to the aromatic group in the pigment molecular structure, thereby capable of dispersing the powdered pigment having an aromatic group. The pigment dispersion solution prepared from the pigment dispersing agent has small particle size, narrow particle size distribution range, and high storage stability, thereby improving the yield of the display product.