Abstract: The surface modifications of diamond were carried out respectively by KH550 silane coupling and polyelectrolyte type surfactant polyethyleneimine (PEI), the effects of KH550 and PEI on surface potential performance of diamond, suspension property of diamond in polyamide imide resin liquid and associativity of diamond and resin were analyzed.The results show that compared to the original diamond abrasive, the surface electrical behavior of modified diamond changes significantly. Zeta potential of diamond increases observably under acid condition, and increases the repulsive force among particles. So it will improve the suspension stability of diamond in the resin liquid. Both surface wettability of resin to diamond and the interface combination are also improved, thus improving the cutting performance of wire saw. The modification effects of diamond modified by KH550 are better than that of PEI.