SiO2 particles were prepared by sol-gel method and further modified with gamma-methacryloxypropyltrimethoxysilane (KH570). A SiO2/PSSS composite was prepared with a core-shell structure, by the in situ polymerization of p-styrene sulfonate sodium (SSS) and the reaction with the KH570-modified SiO2. The SiO2/PSSS composite was optimized by adjusting the mass ratios of KH570 to SiO2, SSS to SiO2 and APS to SSS for control of the particle size and polymer layer thickness. Fourier transform infrared spectrum, contact angle and thermogravimetric analysis indicated that PSSS was successfully coated onto SiO2 particle surface. Transmission electron microscopy images showed that the prepared SiO2/PSSS dispersion had small particles and narrow particle size distribution. The white inkjet ink prepared from the SiO2/PSSS dispersion exhibited excellent thermal and centrifugal stabilities. The white inkjet ink was applied for pretreatment of fabric before colored printing which resulted in a significant enhancement of pattern brightness.