With the extensive application of computer and network technology in the fabric printing industry, digital inkjet printing attracts more and more people. As the particle size of pigment-based inkjet printing ink requires small size. In order to ensure the particle size of the inkjet printing ink to meet the requirement, surfactant is used to modify the property of pigment surface to control the particle size. Through fixed the amount of styrene-maleic anhydride (SMA) to study the effect of grinding conditions on the particle size of ink. Through fixed grinding conditions to study the effect of the amount of styrene-maleic anhydride (SMA) on the modified pigment. The particle size of the modified pigment was tested by using Laser particle analyzer. The shape of the modified pigment and the effect of the modified are observed by using SEM. The results show that the particle size of ink was smaller when the weight of styrene-maleic anhydride (SMA) account for 12.5% of the pigment, the rotate speed of grinding is 2200 r/min and the diameter of mill medium is 1.0-1.2mm.