The service life and performance of diamond bits, to a great extent, are determined by the properties of matrix. The research on matrix materials is mainly concentrated in mechanical erosion and downhole flow field at home and abroad without consideration on electrochemical corrosion and synergy of mechanical erosion and electrochemical corrosion to the matrix material. In this paper, according to the experimental demands and conditions, a slurry erosion test platform is designed by the principle of tribology and electrochemical corrosion, and Co-based matrix is chosen as the experimental sample. The results show that erosion-corrosion of matrix material is caused by pure mechanical erosion, electrochemical corrosion and their synergy as well. So corrosion should be taken into consideration for design of matrix material in corrosive condition.