Abstract: Thirteen kinds of phosphate modifiers are prepared by esterification of P₂O₅ with different ROH and neutra-lization with KOH solution and are blended with some agents in different ratio to improve the surface properties of super-fine CaCO₃.It is manifested in experiments that the modifier phosphodiester is superior to phosphomonoester,and the phosphodiester containing ether chain (AEO-7) and C₄H₉OC₂H₄OH are the best match in surface modification of CaCO₃.The particle of CaCO₃ with grain size d(0.5)＜0.1μm could be obtained with proper application of the phospate modifiers and agents in optimum ratio.