Rapid and efficient dispersion of cementitious material containing large amounts of silica fume, microspheres, and other ultrafine powders is key technology for preparing ultra-high performance concrete. The interaction relation of polycarboxylate superplasticizer (PCE) and silica fume were studied by Zeta potential and total organic carbon method. The results show that surface charge of silica fume in water is negative, and has strong adsorption to PCE and its side chain monomer methacryloxypropyl polyethylene glycol ether (HPEG), while silica fume has weak adsorption to negatively charged main chain sodium polyacrylate (PAANa). In cement paste pore solution, the Zeta potential of silica fume is still negative， but the absolute value declines significantly, meanwhile the total adsorption amount of PCE and its side chain declines, while the adsorption amount of main chain increases. According to the fitting of Langmuir isotherm equation and theoretical calculation, it suggests that the adsorption of side chain structure of polycarboxylate by silica fume mainly comes from hydrogen bonding， which is weakened in cement paste pore solution.