Water-boe raspberry-like PMMA/SiO2 nanocom-posite particles were prepared via free radical copolymerization of methyl methacrylate (MMA) with 1-vinylimidazole (1-VID) in the presence of ultrafine aqueous silica sols.The acid-base interaction between hydroxyl groups (acidic) of silica surfaces and amino groups (basic) of 1-VID was strong enough for promoting the formation of long-standing stable PMMA/SiO2 nanocomposite particles when 10 mol% or more 1-VID as auxiliary monomer was used.The average particle sizes and the silica contents of the nanocomposite particles were in the ranges from 120-330 nm and 15%-20%,respectively.TEM and SEM observations indicated a raspberry-like morphology of the obtained nanocomposite particles.