Pigmented ink will be the main developing trend in inkjet printing technology since it is suitable to all kinds of fiber. In this paper, Encapsulation of organic yellow pigment was prepared by miniemulsion polymerization technique. The pigment was first suspended into the monomer phase treated by ultrasonic irradiation, then added to the water system including surfactant, subsequently the mixture converted into stable miniemulsion droplets through ultrasonic irradiation. The pigment monomer emulsion was polymerized using initiator APS. Experimental results showed that the effect of the surfactant on the yields was not very significant, but the encapsulating ratio reduced with an increase of surfactant, the costabilizer hexadecane was the key factor to influence the size of the pigment-polymer particles, and the encapsulating ratio enhanced obviously in the presence of the hexadecane. With the ratio of monomer (styrene) increasing the encapsulating ratio enhanced, and the ratio of polystyrene particles increased too. TEM photographs indicated that the particles have core-shell structure.