Abstract: Ni₃Al/diamond composites were prepared by vacuum hot pressing.The effects of different sintering additives on the mechanical properties and microstructure of the composites were studied, and the drilling performance of the Ni₃Al/diamond drilling bit was tested.The results show that, after the addition of Cu-Sn, Ni-Cr, and Co sintering agent ranging from 0 to 30vol%, the density, bending strength and hardness of Ni₃Al/diamond tool bit are improved.With the content of Ni-Cr and Co increasing, the bending strength of Ni₃Al/diamond composites is increased.Enrichment of the Cr elements in the Cu-Sn and Ni-Cr sintering additives is observed on the surface of the diamond.The Ni₃Al/diamond composite materials supplemented with Cu-Sn and Ni-Cr sintering additives were prepared into a tool for drilling and testing.The results show that the failure forms of Ni₃Al/diamond composites with Cu-Sn and Ni-Cr sintering additives can be divided into three forms:micro crushing, abrasion and macro crushing.The phenomenon of falling off of the whole diamond is not found in the drilling test, indicating that Ni₃Al based has a large holding force on diamond and the strength is high.