The multilayer granular structure has been developed and has proved to be a promising candidate for extremely high-density magnetic recording. Recently, the properties of friction and wear of the structure have been studied and the in-situ nanoscale protection concept has been proposed. In this paper, two series of CoCrPt-C multilayer samples with various interlayer carbon concentration and with/without carbon overcoat (top layer) are compared, having been prepared by using facing target sputtering (FTS) and normal dc sputtering (DCS), respectively. The corrosion resistance of the sample is investigated using environmental and electrochemical methods. Optical microscopy and time-of-flight secondary ion mass spectrometry are used to characterize the corrosion test samples. For the samples prepared by FTS, both top and interlayer carbon can provide protection for the media. In terms of the samples prepared by DCS, the carbon layer may increase the porous density during the corrosion process. It is concluded that the sp 3/sp 2 ratio of the carbon is the most important consideration in nanoscale protection for the granular thin film media. Raman spectroscopy results further confirm the conclusion.