Brazing experiments of polycrystalline CBN abrasive grains and AISI 1045 steel matrix using 95(72Ag-28Cu)-5Ti (wt.%) filler alloy were carried out at the heating temperature of 900 °C for the dwell time of 8 min. The microstructure of the brazing interface among PCBN grain, Ag-Cu-Ti alloy and steel matrix, was characterized with optical microscope, scanning electron microscope and X-ray diffraction equipment. Grinding performance of the brazed polycrystalline CBN abrasive tools was evaluated experimentally by comparison with monocrystalline CBN counterparts. The results show that the reaction layer between polycrystalline CBN abrasive grain and Ag-Cu-Ti filler layer consists of the compounds of Ti-nitride, Ti-borides and Ti3AlN. The resultants have played an important role in terms of strong chemical joining at the grain-filler interface. The brazed abrasive tools with polycrystalline CBN grains have given higher material removal rate and longer service life than that with monocrystalline CBN ones.