We have studied the interface formation process of Pb/Ni (001) system by means of tunable-sampling-depth electron energy loss spectroscopy (TELS) and Auger electron spectroscopy (AES). During the deposition of Pb, the AES peak height ratio of Pb to Ni versus time of deposition consists of three segments with the two turning points corresponding to 1 mono-layer (ML) and 2 ML respectively, indicating the Franck-Van der Merwe, i.e. layer by layer growth mode. Also during the Pb deposition, the Pb 6s band ELS peak appears as the Pb coverage is beyond 1 ML, while the Pb bulk plasmon peak appears at about 2 ML of Pb coverage. During the whole process of deposition and annealing, the ELS peak position and width of the Pb bulk plasmon peak, the 6s band peak as well as the Ni 3p band peak maintain their own pure metal values, and there was no new bulk plasmon peak. In view of all these facts, we have reached the conclusion that there is no intermixing of Pb with Ni and the interface of this system is abrupt.