Abstract: As a part of friction pair, the inner hole surface of tooth wheel drill bit was electroplated with silver to improve the sealing performance and service life of the bearing. The effect of surface roughness on quality of silver coating on inner hole surface of tooth wheel drill bit were analyzed by means of XRD analysis, thermal shock test, metallographic examination, SEM and energy spectrum analysis. The results show that the appearance and purity of the silver coating on the two drill bit were basically the same, the difference was mainly due to the different surface roughness of the matrix, which caused the difference in binding strength of silver coating. Reducing the surface roughness of the matrix can improve the binding strength and wear resistance of silver coating.