Effects of some alloying additives such as Cr, Co, Ni, Mn, Al on the microstructures, resulting fracture surfaces of bronze base bonds and diamond composites as well as the bonding between the metal bonds and diamond grits were studied. Experimental results revealed that under the hot pressing conditions sufficient alloying couldn’t develop as it does in the cast bronze. The degree of segregation varied with the melting point of the alloying elements. The metal with higher melting point led to a more serious segregation. Addition of strong carbide formation elements like Cr, Co could improve the bonding between the metal bonds and diamond grits and the retension of metal bond for diamond was enhanced in a way. However the addition of Al, Mn and Ni did not bring much improvement on the bonding between the metal bonds and the diamond grits.