Abstract: The adsorption of sodium dodecylbenzenesulfate(SDBS) on nano-sized CaCO_3 in aqueous system was studied so as to further analyze the dispersing mechanism of the nano-sized CaCO_3 in aqueous system with SDBS as dispersant.The adsorption amount of SDBS on nano-sized CaCO_3 was determined by using UV/VI spectrometry.The change of Zeta potential of dispersion after adsorption of SDBS and the stability of adsorption were discussed.The experimental results showed that the adsorption amount of SDBS on nano-sized CaCO_3 increased with increasing the concentration of SDBS solution and reached saturated adsorption when the concentration exceeded(2 g/L.) pH value had an impact on the adsorption amount and the amount of adsorption at pH=7 was larger than that at pH=11.After SDBS was adsorbed on nano-sized CaCO_3,a great change of Zeta potential of the dispersion was observed.The adsorption of SDBS on nano-sized CaCO_3 was a spontaneous process and this adsorption was rather stable.