Abstract: Aimed at the problem of resistance to soldering heat(RSH) performance degradation of terminal electrodes with SnPb surface coating in multilayer ceramic capacitors(MLCC) devices, the microstructure and components of SnPb coating were studied with SEM and its attached EDS, and the RSH performance degradation reasons were found. The results show that during the firing processes of silver termination paste, the remains of glass phase were produced, which resulting in the discontinuous of the surface SnPb coating and deterioration of the weldability of the terminal electrodes of MLCC because the glass phase was no-conductive material.