Grinding has an important effect on the chemical composition of the mineral surface. In this study, the interaction of galena and chalcopyrite during grinding was studied by time-of-flight secondary ion mass spectrometry (ToF-SIMS), principal component analysis (PCA), and inductively coupled plasma optical emission spectrometry (ICP-OES). Results showed that during mixed grinding, the surface compositions of chalcopyrite and galena became more similar, and the dissolution of chalcopyrite and galena was promoted. Grinding not only results in the adsorption of lead ions released from galena to the chalcopyrite surface, but also results in the adsorption of copper and iron ions released from chalcopyrite to the galena surface. The Cu, Fe, and Pb atoms on the surface of chalcopyrite and galena may be bonded in the form of Pb-O-Cu, Pb-O-Fe, and Pb-S-Cu. This study can provide a surface chemical basis for controlling the grinding process of copper-lead sulfide ore. (C) 2020 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.